Continuity mistake: Leaning against the car during the riots, Joker's face paint is smeared with a tear exactly the way it was when he walked out of the subway before the Murray Franklin show. But of course it went through a lot of fixing since. (01:46:45)
Continuity mistake: The first time we see Randall, he hangs his clown suit next to his locker; his right hand drops, but in the next shot it starts still up. (00:15:50)
Continuity mistake: In the last couple of cuts preceding Arthur's gun accident in front of the kids, the nurse's hands are not where they should be at the cut; her hands are on the kid' shoulders, then ears, before the cut she raises them to dance on the spot, but they are back on his shoulders in the next shot. The baby patient himself when Arthur drops the gun suddenly has his hands up under the chin. (00:28:25)
Continuity mistake: Just before Arthur is hit with the yellow sign there is a person behind him that disappears between shots. (00:02:45)
Continuity mistake: After Arthur steals the file from the guy in Arkham he runs and the file moves from one arm to the other. (01:13:10)
Continuity mistake: After Arthur took off the stolen jacket and hat when talking to Wayne he places them in the sink, but in the next cut they disappear. (01:05:00)
Suggested correction: You don't see the sink containing the clothes anymore after he puts them down.