Revealing mistake: In the beginning of the Five Points battle it happens very often that people get hit badly with a sharp weapon but don't receive any wound. Watch for example in slow-motion how Bill sets out to mow down victim after victim with his cleaver. Later into the fight it becomes a lot bloodier, and sometimes the blood seems to come out of the weapon (e.g Monk's club seems to have a generous blood reservoir). (00:08:15)
Revealing mistake: In the middle of the battle of Five Points Monk swings his club horizontally at shoulder level, but the swing ends on a victim's ankle. When the bones break it's very obvious that it's a prop. (00:09:15)
Revealing mistake: In the battle of The Five Points, there are at least two instances where you see "blood" splattered over the lens. (00:09:35)
Revealing mistake: When Amsterdam meets Bill for the first time as an adult Bill is playing Whist. Because he is pissed with a guy whose bet isn't high enough he pulls his knife and pins the man's hand to the table. When he does so the hand isn't anywhere near the point where the knife goes in, and when Bill pulls out the knife again you see that it was stuck in the table and the man's hand was resting next to it. (00:36:00)
Revealing mistake: When Jenny gets mugged at the docks, a thug hits her in the stomach with a large wooden club. The club is obviously rubber, as it bends almost ninety degrees after hitting Jenny. (00:58:20)
Revealing mistake: When Bill gets shot at the theater blood gushes in quantities that could only come from a main artery. His obvious fitness in the following sequences speaks against it, though. (01:13:40)
Revealing mistake: The scene where Amsterdam and Jenny are in the room together above the tavern, shortly after Bill's assassination attempt, Amsterdam pushes Jenny up against a 12 inch by 12 inch wooden beam. The problem is when he is pushing her up against this beam, you can see it flexing with the weight. Then Amsterdam is holding the beam, you can see that the beam is some type of cloth because the slight touch of his hand makes it dent in. (01:20:45)
Revealing mistake: In the scene when Bill confronted Monk outside the barber shop, Monk invites Bill in to settle their score the democratic way. As Monk led the way, Bill threw his big butcher knife into Monk's back. The knife can be seen bouncing off Monk's back onto the ground. (02:19:05)
Revealing mistake: In the last scene where Amsterdam is crossing the black man's arms, wait until the camera pans onto Jenny. In the background there is another dead man and you can see him breathing pretty heavily. (02:29:30)
Revealing mistake: When Amsterdam is looking at the dead bodies laid out with candles at the end of the movie, the dead are shown breathing. (02:31:45)
Revealing mistake: In the scene where Bill has Amsterdam on the table, he begins headbutting him. You don't even have to look closely to see that Amsterdam's head is obviously just a dummy head with hair sewn on it. You can even see Bill headbutting it, and the head bends a significant amount, just like rubber. If it were Amsterdam's actual head his skull would be shattered in several places and he'd be killed instantly.
Revealing mistake: In the first fight scene, Priest Vallon stabs a man from behind with his sword. You see the sword go under his arm where he holds it there.
Revealing mistake: In the Five Points battle scene, in the beginning of the movie, look at Bill the Butcher's blades when he walks through the crowd towards Priest Vallon. There is no sign of blood on them, even after he stabs a lot of people.
Revealing mistake: When Bill the Butcher kills Priest Vallon at the Five Points battle, the blood squeezes from Vallon's flank wound in an obviously fake way.
Revealing mistake: During the theatre scene, when the camera is behind the hanging actor and the crowd begins to throw fruit at the stage, the screen very briefly shakes; the cameraman was hit.
