Sengoku telling Ace who his father was.
Hearing/reading that for the first time was a real, WTF moment, simply because of the unconvincing way it was fed to us. It was so on the nose and over-expository, he was practically speaking to the viewer. And then on the second viewing, it occured to me, he's doing a publicity stunt. Since the execution is being broadcast, he is playing to the cameras. It might've helped however if he had refered to Ace in the third person rather than the first.