The Green Databook revealed that Sanji's original name was going to be 'Naruto'. However, as the ninja manga Naruto was about to be serialized with Jump, Oda changed the name to prevent confusion.
A scene of young Sanji beginning to smoke during his early days at the Baratie was not shown in the anime, possibly because it showed a child smoking and implied that smoking was a way of seeming mature.
The manner in which Zeff lost his leg was also altered. While the anime showed him cutting off his leg in order to escape an anchor's chain and get Sanji safely to shore, the original story in the manga implied that he had eaten his own leg in order to survive while he and Sanji were stranded, as he had given Sanji all of their food rations.
Like all of the Straw Hats, (except Luffy) his time alone after being teleported away by Kuma was extended in the anime.
It showed that he was treated by what appeared to be a beautiful woman named Tibany. Sanji then followed her, only to discover that "she" was an okama. Unfortunately for him, due to a miscommunication between the two of them, Sanji is interpreted as an okama and is soon seen running away. The anime version shows Caroline (the substitute Queen of Kamabakka Kingdom) turning Sanji into an okama. Later, upon receiving the news about Ace's death and the Battle of Marineford, the shock of it turns him back to his usual self.
Also in the anime, Sanji instantly falls in love with Ivankov's female form, despite knowing "she" would not be interested in men. He attempts to ask about Luffy through gestures of romance. He snaps out of it when Ivankov turns back into a man, angering Sanji and crushing his hopes of meeting a real woman.
Their fight is shown, with Sanji attacking Ivankov with Diable Jambe. Ivankov pretends to be defeated by this but then effortlessly overpowers Sanji, surprising his Okama followers. Iva then unleashes a barrage of "44 - Aesthetic Technique! Hair Removal Fist", "Death Wink", "Hell Wink", and "Galaxy Wink" leaving Sanji on the ground bloodied and beaten to an inch of his life. Ivankov then hands Sanji a newspaper since the news of Luffy has already been made public.
In the manga, after one of the okamas tells Sanji that they hope to see him again, he replies by saying he does not want to see them again showing "the finger". In the anime, this was censored so he replies with the same answer but puts his right hand across him and moving it to the lower right.
Sanji's lighter seen during the Punk Hazard Arc and in One Piece Film: Z. It was given a realistic version made by DuPont. The lighter was designed by Oda himself. It has the shape of a woman sitting, leaning on her legs.
Sanji makes a cameo appearance in Sayonara Zetsubo Sensei. During the character Meru's introduction, Harumi is seen reading a yaoi manga featuring Sanji and Zoro. Also, in her room, there are action figures of Luffy, Zoro, Sanji and Sogeking. Also, in the same series, during Nozomu's escape from an evil organization, his silhouette is visible along with the silhouettes of Nami, Luffy, Usopp and Zoro plus two unidentified pirates; one that could be Robin and one that looks like a human version of Chopper's Heavy Point wearing a sash and a bandanna.
In the MMO fighting game Rumble Fighter, a user suggested a Sanji based fighting style for the game using sprites from a Wonderswan One Piece game in order to give the developers a general idea. The developers liked it, and decided to create this fighting style, although naming it "Red Leg" instead of the actual name, "Black Leg".
In the anime Working! there is a character named Satou Jun who closely resembles Sanji, due to them both sharing the same appearance, both working as chefs and both seen to regularly smoke.
In the original Japanese manga, the Japanese anime, the uncut FUNimation dub, and the Viz English manga, Sanji is a chain smoker. In the 4Kids anime, Sanji instead sucks on lollipops (because of the audience the dub was aimed at). For the aired, edited FUNimation version, the cigarette was completely edited out and any scenes that show him lighting cigarettes or other such actions were redrawn. The same was done in the Singaporean English dub by Odex.
The lollipop from the 4Kids version.
The cigarette from the original.
In the FUNimation subs his epithet of "Black Leg" (黒脚 ,Kuroashi) is translated as "Black Foot". This is because Ashi can translate as either "Leg" or "Foot".
In the English-language manga, Sanji often uses "Crap" as an adjective while speaking (when calling Crocodile, he refers to the restaurant as "Restaurant Le Crap" ("Crap Café" in the uncut FUNimation dub). This is an attempt to convey both his extremely coarse speaking style in Japanese, as well as his use of "kuso" (roughly "feces") as an expletive; fans often translate it as "shit" because of his manner of speech. For example, he often calls Zeff "Kuso-Jiji" (roughly "shitty-geezer"). In other fan translations, it is rendered as "old fart" or "old man".
In the English anime produced by 4Kids, he simply calls Zeff "old-geezer" or "old fart" (in fansubs, he is also referred to by this name), and "crap-geezer" in the English manga. Also, in the 4Kids English dub, Sanji has an extremely nasally Brooklyn accent, while in the FUNimation version, there is no accent.
Sanji's personal jolly roger (post-timeskip) as detailed in the One Piece Magazine.
Baby Den Den Mushi displays Sanji's eyebrows prior to the timeskip.
Sanji has his own jolly roger, as does the rest of the crew. It has Sanji's right curly eyebrow, fork and knife for cross-bones, and a chef's hat placed on the top of his head.
His post-timeskip jolly roger is similar, except his chef hat is slanted to the right which hides his right eye, the skull has a goatee and cigarette, and the crossbones fork has four prongs instead of three.
Sanji's left eye was considered one of the "mysteries" of One Piece. As of Chapter 598, the mystery has been solved. After the two year separation, Sanji's hair style changed revealing his left eye and covering his right. This also reveals Sanji's eyebrows are asymmetrical, with both featuring a clockwise curl on the right hand side, and were both halves of Sanji's face to be uncovered at the same time, this anomaly would be fully apparent.
As a child, Sanji was imprisoned and forced to wear an iron mask. This resembles the story of the Man in the Iron Mask, allegedly a member of French royalty who was imprisoned in a similar manner.
Duval shares this resemblance, although he wears a mask from choice to hide his face.
The reason for Sanji's massive nosebleeds is from the joke that Japanese people (like Oda) have high blood pressure. Therefore, they get nosebleeds when they are sexually aroused. This joke is a very common cliche in manga and anime.
During the Fishman Island Saga, it became a running gag that he would have exaggerated nosebleeds each time he saw a beautiful woman, until the crew acknowledged it as an actual problem. This is likely to emphasize the idea that, after two years in "Hell," seeing an actual woman makes his heart race.
Sanji has smoked two brands of cigarettes, King Ground and Death.
There is a plot hole in the series when Sanji is unaware of a Devil Fruit user's inability to swim in the Baratie Arc, but he states that he became aware of this when he was a kid during the Thriller Bark Arc.
Sanji has a habit of saying "Mellorine" (an alternative to ice cream made from fats other than the butterfat normally used in ice cream) when looking, talking, or commenting about a beautiful woman. This carries over to the FUNimation English dub. His personalized honorific for Nami "Nami-swan" (developed from san) also carries over.
Sanji's knife from volume 7 page 18 (chapter 54) had writing on it saying "Hokuto no Ken" referring to a series from Oda's elementary school days called "Fist of the North Star".
As revealed in the Jaya Arc, Sanji is terrified of bugs and is especially scared of spiders. A phobia he shares with Nami, as they both panicked when Usopp found a tarantula.
He, Luffy, and Usopp all claim to have never been sick, and thus do not know what it feels like. 
His name (三時,san-ji?) can mean "three o'clock" or "three o'clock snack". This points to a wider theme in Sanji's character, revolving around the number 3:
Sanji shares some similarities with Portgas D. Ace, as they are both pirates, and they both considered another person to be their own fathers (Zeff for Sanji, Edward Newgate for Ace).
They are both the sons of kings but are not referred to as princes.
Sanji is the only Straw Hat shown so far to have biological siblings; Nojiko is Nami's adopted sister, while Ace and Sabo are Luffy's sworn brothers. Ironically, while Nami and Luffy adore their siblings, Sanji and his brothers actively despise each other.
In the Pirate Warriors series of video games, Sanji cannot attack female characters. This applies to both when the player is controlling him and facing female enemies, as well as when the player encounters him as an enemy while controlling a female character. When selecting a stage where female characters appear as enemies, if Sanji is selected by the player, a warning box will appear that points out Sanji's weakness to female characters and the player will be given the option to change to another character or ignore it and play the stage as Sanji. Generally there are two methods for dealing with female characters while playing as Sanji in the Pirate Warriors series, one is to avoid fighting them if possible (this may not be possible if a female opponent's defeat is required), while the other is to use support characters to deal with female opponents.
In Pirate Warriors 2 , despite Sanji has been affected by Mad Dial. He will still retain his principle and will not kick any women due to his strong principle to not kick any woman even it means his death.
In One Piece: Burning Blood, Sanji has a special attack "I won't kick a woman, even if it means my death!" that causes all his attacks (including his special and ultimate moves) to comically change into hearts and causes his health meter's portrait and the face on character model to change to his "heart eyes" face, when fighting female characters (as well as Bon Clay (Clone) who is considered a female character in his DLC "Nami Mode" form). Unlike the Pirate Warriors series, Sanji can still attack female characters and "hearts" he produces can cause minor damage to female opponents. However Sanji is still weak against female characters, so it is best to switch to another teammate (when fighting as a team) and/or use support characters that can inflict damage. Players can also take advantage of Sanji's weakness by using and/or swapping (in team battles) to a female character as an effective way to counter him.
In Chapter 831, the illusion of Sanji is seen with a lollipop instead of a cigarette which, coincidentally, matching with his appearance in the 4Kids dub.
Sanji's ability to harden his leg with Busoshoku: Koka is quite fitting and somewhat ironic, given that it effectively matches his epithet, "Black Leg".
Although Sanji was not introduced with a family name, Charlotte Cracker referred him as "Vinsmoke Sanji". Sanji later affirmed this name when putting up an act against Luffy and Nami.
Sanji has the ability to read any woman's three sizes (Bust - Waist - Hip) and it was Sanji who, according to Oda, identified Robin and Nami's measurements.
Sanji is the only one of the five Vinsmoke siblings to inherit his parents' blonde hair color because the genetic modifications the other four have adapted to changed their hair colors in the process.
Sanji's favorite foods are spicy seafood pasta and stuff that goes with black tea. His least favorite food is konjac because it has no nutritional value.
Sanji also don't like ice cream, the same as Zoro, Nami and Franky.
If the Straw Hat Pirates were a family, then Sanji would be the second son.
This statement gained credence when Sanji was revealed to be the third son of the Vinsmoke Family. However, Sanji's actual lineage is one son younger than what Oda originally stated as a comparison.
↑ 8.08.1SBSOne Piece Manga — Vol. 69 (p. 66),
First fan question: Oda-sensei, I have a question. Please tell me the current profiles (birthday, height, age) of all of the members of the Straw Hat Pirates! Second Fan question: Oda-sensei! Please tell me the order in which the members of the Straw Hat Pirates joined the crew! I'm really grateful!
↑ 9.09.19.29.3SBSOne Piece Manga — Vol. 84 (p. 150),
Fan question: Since in chapter 833, you said all four kids were born on the same day, does that mean that Ichiji, Niji, and Yonji are all 21 years old, born on March 2nd? How old is Reiju? Also, tell me the blood types and heights of the other Vinsmoke siblings.
↑ 10.010.1SBSOne Piece Manga — Vol. 15 (p. 90),
Fan question: Oda-sensei!! I've been thinking about this a lot... what are Luffy, Zoro, Nami, Usopp and Sanji's birthdays? Tell us!!
↑One Piece Manga — Vol.
84 Chapter 843 (p. 16),
Sanji affirms his name as "Vinsmoke Sanji".
↑SBSOne Piece Manga — Vol. 68 (p. 64),
Fan question: Oda-sensei, hello. In regards to Sanji, I feel that he looks like Leonardo Di Caprio-san from the western movie, "Romeo and Juliet". My friends say I'm dead wrong. Is Sanji's appearance based on someone in particular?
↑SBSOne Piece Manga — Vol. 6 (p. 104),
Fan question: When the question came up about Nami's three sizes (Bust-Waist-Hip) you said "I promise!!". So when are you going to tell us?!!
↑SBSOne Piece Manga — Vol. 37 (p. 146),
First fan question: Good day, Oda-sensei. I am Richie Usapon, president of the Japan Healthy Men's Organization (current members: 1). I have a request to make of you, Oda-sensei... actually to Sanji-san. "PLEASE TELL ME ROBIN'S MEASUREMENTS!!" I am so, so so serious. Second fan questiton: Hi, Oda-sensei! In Volume 36 you were saying that Nami's breasts had grown in size from years ago, so what are her 3 sizes now? I'd bet that every man in the country is dying to know this, so don't hold out on us!
↑SBSOne Piece Manga — Vol. 58 (p. 100),
First fan question: Odacchi! Helloooooes! I know this is a bit sudden, but please go ahead and tell me the Three Sizes of Hancock-sama! second fan question: Odacchi~! This is the first time I send a letter! There's one thing I've been wanting to ask for a long time... What cup size are Hancock's breasts? (I'm hoping they're about J-cup).
↑SBSOne Piece Manga — Vol. 69 (p. 166),
Fan question: About the mystery of Nami-san's New World bust size from volume 66, I would like to provide my opinion as an employee at LADIES' INNER. Nami-san's bust size is most likely a "J Cup". There is a possibility that she may have even grown bigger than this. ...If my calculations are correct, her band measurement is 63 cm, and her bust is 98 cm. If we were to use these measurements, she would end up being a "K"; however, right now in Japan, there is no such thing as a "K" cup. She'd have to order from overseas. Oui, in other words, non-standardized!!! Well, personally, I'd say that Nami-san is a "Nami Cup". (Boiing)
↑SBSOne Piece Manga — Vol. 87 (p. 62),
Fan question: Oda-san, hello!! Vinsmoke Judge and Sanji's hair is yellow. If this is so, why do the four remaining Vinsmoke kids dye their hair when they were little? Or was it the caused by the Lineage Factor?
↑SBSOne Piece Manga — Vol. 45,
Fan question: Luffy's favorite food is meat. What about everyone else on the crew? And you yourself, Oda-sensei????
↑SBSOne Piece Manga — Vol. 73 (p. 144),
Fan question: I was looking up trivia on the Straw Hat Pirates, and I found that although they've all been given a favorite food, I can't find anything about their least favorite. So what are each of the Straw Hat Pirates' least favorite foods?
↑SBSOne Piece Manga — Vol. 84 (p. 150),
Fan question: Oda Sensei!! Please tell me who from the Straw Hat Pirates likes ice cream, and who don't?
↑SBSOne Piece Manga — Vol. 79 (p. 142),
Fan question: In the Straw Hat Pirates, Sanji is obviously the one who is the best at cooking, but who else is good at cooking? What is everyone's speciality dish?
↑SBSOne Piece Manga — Vol. 38 (p. 146),
Fan question: Odacchi! I read One Piece! And laugh! And cry! I'm such a huge x(infinity) fan! So, I have a question for Odacchi and the Straw Hat Pirates! There are Spring, Summer, Autumn and Winter Islands. Which is everyone's favorite?
↑ 37.037.137.2SBSOne Piece Manga — Vol. 40 (p. 66),
First fan question: Hi there, Odacchi! I've wondering about something you might be able to answer for me! Since Chapter 334, Nami's been wearing the same tanktop with a 3 on it. What does it mean? Second fan question: Hello, Oda-sensei. If you have specific colors for each main character of One Piece, please tell us what they are. Second fan question: Hello, Oda-sensei. If you have specific colors for each main character of One Piece, please tell us what they are. Third fan question: I have a question!! If Chopper has such a splendid blue nose that he can tell where his crewmates are at any time, what do all the members of the Straw Hat Pirates smell like? Does Luffy have a rubbery smell?? Let's ask Chopper.
↑SBSOne Piece Manga — Vol. 48 (p. 26),
Fan question: Hello, Odacchi! I have a question; will you hear me out? ...Oh, you will? Thanks! Here goes. In the song the Straw Hat Pirates sing called "Family", they have a line that goes "We're not acquaintances, we're not friends, we're family". If the Straw Hat Pirates really were an actual family, who would be the dad, and who would be the mom?
↑SBSOne Piece Manga — Vol. 20 (p. 26),
Fan question: Oda-sensei, out of the 5 crew members Luffy, Zoro, Usopp, Nami and Sanji, what animals do you think they most resemble?
↑SBSOne Piece Manga — Vol. 56 (p. 144),
Fan question: Nice to meet you, Oda-sensei. I have a question. If One Piece was set in the real world, which countries would the nine Straw Hat Pirates come from?
↑SBSOne Piece Manga — Vol. 59 (p. 96),
Fan question: Hello Oda Sensei~! Out of the blue but can you write what is inside luffy's head? oh and your head too--. my friend's head is half pervert and half games.
↑SBSOne Piece Manga — Vol. 60 (p. 206),
Fan question: A question to the Hana Hana no Mi user, flower loving Robin <3. Which flower would suit each of the Straw Hat Pirates? Sister Robin can go with a flower she likes <3 by I like cosmoses.
↑SBSOne Piece Manga — Vol. 66 (p. 162),
Fan question: Hello Oda-sensei! In volume 62 when Sanji meets the mermaids and blows a shower of nosebleed, Chopper was saying his blood type was "S", but that sounds really different! What are the other blood types? If it is okay with you, I would like to know the blood types of all the Straw Hat Pirates!
↑SBSOne Piece Manga — Vol. 67 (p. 182),
Fan question: In chapter 654, Chopper turns down Nami's invitation to join her in the bath, saying "I wiped myself down the day before yesterday", right? Is it because he's a boy? Or a fruit user? Or maybe... because he's an animal? I'm also interested in the bathing information for the rest of the Straw Hat Pirates.
↑ 46.046.1SBSOne Piece Manga — Vol. 72 (p. 46),
First fan question: It seems that Trafalgar Law, in the midst of his alliance with the Straw Hat Pirates, gives them some nicknames. What are all the things he calls the various members of the crew like Zoro and Franky? Second fan question: If the Straw Hat Pirates were different prefectures of Japan, what they would be? For example, would Nami be from Ehime, I'd love to hear from you!
↑SBSOne Piece Manga — Vol. 74 (p. 126),
Fan question: I would like to know the Straw Hat Pirates' bed times and wake up times!
↑SBSOne Piece Manga — Vol. 76 (p. 42),
Fan question: If the Straw Hats never became pirates, what would their careers of choice be?
↑SBSOne Piece Manga — Vol. 85 (p. 78),
Fan question: Who is the fastest crewmate when they run a 50-meter race?