Continuity mistake: When Tommy is shot, Tuddy is holding his shirt, but in the very next shot, he isn't, and he's much further away from him.
Continuity mistake: After Tommy shoots and kills Spider, Henry sits back up and puts his hands down from covering his ears twice.
Continuity mistake: After Karen's been harassed by her neighbour, Henry drives her home and tells her to walk home. When Henry steps out, she's nowhere to be seen. She couldn't have walked all the way to the house in that short time. She couldn't have run, either, being as weary as she was.
Other mistake: Billy Batts is killed and buried in June 1970. Later on, Jimmy tells Henry that they have to dig the remains up due to condos being built on the site; Henry says "that was 6 months ago", putting the time frame at December 1970. In the car trunk-cleaning scene that follows, the trees are in full green foliage and Henry is dressed for summer. (02:36:00)
Continuity mistake: When Karen is pointing a gun in Henry's face, the close up is different from the one she has in her hands. (01:13:00)
Audio problem: When Billy Batts is explaining to the guys about Tommy's shining his mouth doesn't match up to the words.
Audio problem: When Janice is handing the dog to Tommy at her apartment he's talking but his mouth isn't moving.
Continuity mistake: When Karen is over Henry pointing the gun at him, the trigger is pulled all the way back. The gun also goes from blue steel to silver.
Continuity mistake: At the beginning of the movie they pull to the side of the road and stab and shoot the not yet dead man in the trunk. In this scene Jimmy shoots him 4 times. Later, when they get to this scene in the story and show it again in slow mo, Jimmy fires the gun 5 times. (01:00:34)
Suggested correction: Jimmy shoots the gun 3 times in each scene.
Factual error: Unless Henry was intoxicated or heavily medicated during his sleep, it would have been impossible for Karen to have climbed on top of him in bed, point a gun at his head, without him ever feeling her body on top of his.
Continuity mistake: Henry picks up Karen from a phone booth after her neighbor tries to attack her. The left side of her shirt is dirty. When Henry drops her at home and beats up the neighbor, Karen's shirt is completely clean. (00:39:36 - 00:41:10)
Continuity mistake: After Henry gives Paulie a share of the money he took from the air port, Paulie tells him to say that he got the rest of the money playing Craps in Vegas. Paulie's left hand is around Henry's back with his hand flat out on his shoulder. When it cuts to a close up as Paulie is playfully slapping his cheek with his other hand, his left hand is now suddenly balled up in a different position on Henry's shoulder. (00:35:30)
Continuity mistake: While Henry is in the shower pounding on the tiles after hearing about Lufthansa, his bar of soap changes hands between shots. (01:33:00)
Revealing mistake: Young Henry's eyes are distractingly bad with obvious contacts that look really fake.
