Continuity mistake: When Remo Gaggi is talking to Andy Stone about Ace cussing out the Board, there's a pack of cigarettes beside Gaggi in his car. The camera angle changes to show Stone's face, who is outside the car, and when it flips back to Gaggi, there is a Zippo lighter in place of the cigarettes. The camera goes back to Stone, and when it comes back again, the Zippo is gone and the cigarettes are back. And to top it all off, not once did Remo smoke in this scene.
Continuity mistake: In the scene where Sharon Stone is talking to Joe Pesci about how De Niro had his guys beat up James Woods, there are 4 security monitors on the desk behind Sharon Stone. First, the top left monitor goes out. Next only the bottom right monitor is on. Then all four monitors are off. Finally, all four monitors are on again. (01:18:05 - 01:19:20)
Continuity mistake: When DeNiro catches the cheats at the card tables, he takes the one with the beard to smash his hand with a hammer. In the first shot the guard is holding the cheat down by the wrist, but in the next shot the guard's hand is up by the guy's elbow.
Continuity mistake: When Ginger is arguing with the gambler at the craps table about "giving her a bigger cut", the man reaches for her purse to show her the chips she's been stealing from him. As she pulls the purse back, the gold chain strap breaks. The next shot of Ginger shows a repaired chain.
Continuity mistake: Jennifer has the diamonds inside her hair bun and she's shaking it to retrieve the diamonds onto the table. As Santoro slaps her face as a gesture to thank her and for her not to get smart with him, her hair bun comes loose and falls out into a pony tail. The next shot then shows Jennifer with the hair bun perfectly groomed again on top of her head.
Continuity mistake: When Nicky has the guy's head in a vise, after it squirts Nicky's hair changes between shots, from neat to messed up.
Continuity mistake: In the scene towards the end before De Niro's car explodes, in the first shot when he opens the door its window is down as he gets in the car, but in the next shot as his motions are replayed, when he opens the door that window is all the way up, then it's down again in following shots. (02:46:00)
Continuity mistake: When news on Robert De Niro not having a casino license first hits the airwaves, the news broadcast displays a still picture of Joe Pesci having a conversation with his friend Frankie. The picture that they use is when Pesci and Frankie have tooth picks in their mouths because they don't want FBI agents lip reading what they are saying. But that didn't happen until later on in the movie. So how could they have displayed a picture of a conversation that hadn't taken place yet?