Continuity mistake: Right after Paul goes home with the doctor, the doctor and his wife are clearing the dinner table talking about Paul staying at the house. The wife turns to the dinner table and is holding 2 napkins. The camera angle changes and the wife is now seen walking 2 glasses over to the sink.
Continuity mistake: In the chase sequence where Paul Vitti and Dr. Ben Sobel are being chased in Sobel's Grand Cherokee, we see the car plow head-on through a bank's drive-thru ATM machine. Yet later on when we see a shot of the car's front grille again, and the car doesn't have any front end damage from the crash.
Continuity mistake: In the scene where Billy Crystal and Robert De Niro are eating at a Sushi Bar with a crew of people, Billy Crystal is acting up due to a reaction of medication and alcohol. Robert De Niro threatens Billy by telling him that he would stick a f***ing fork in his eye; when De Niro is waving the fork around you can plainly see a noodle on Billy Crystal's face, however, when the shot changes a second later, and shows Billy Crystal and Robert De Niro, there is nothing on Billy Crystal's face; the noodle has disappeared.