Factual error: When Amsterdam kills the man that shot Bill the Butcher in the shoulder at the theater, you can see bananas on the floor. Bananas were traded in the U.S. only after the Civil War. (01:13:50)
Continuity mistake: After Jenny gets mugged at the dock, the shot shows her pulling herself to a standing position on a crate. In the next shot, from farther back and up high, she is crawling over to the crate she just pulled herself up on. (02:20:55)
Continuity mistake: When Amsterdam arrives in New York City and is talking to his new friend, the bag he is holding switches from being held under his arm (camera shot from front) to being carried on his back (camera shot from the back). This happens at least four times in a row during the same scene. (00:22:55)
Answer: Well, rather obviously, Amsterdam hates him because he killed his father. I mean, wouldn't you? It hardly matters that the fight was fair and that Bill showed respect about it, Amsterdam's not exactly likely to turn round, say "oh, that's alright then" and walk away. William Cutting (or William Poole, as he was in reality) was a ruthless, vicious man, who pretty much stopped at nothing to cement his control of the area. Whether he was actually worse than many of the others is questionable, but the film is based on Amsterdam's view of things - in that view, Bill is the enemy and we're supposed to see him as such.
Tailkinker ★