Continuity mistake: In the flashback scene (where Cassie has the crazy long hair) we see "young" Cassie perform a routine in the studio. Zach comes out of the shower towelling his hair and watches her. We see his hair is messed up having just been roughly dried with a towel. The next shot is Cassie dancing, then the next shot is back to Zach, and this time his hair is combed nicely down.
Factual error: In the shot of Florence with several bridges and the river shown, cars and motorbikes can be seen going across the lowest bridge in the shot. (00:10:10)
Other mistake: During the epic love scene between Helen Shaver and Patricia Charbonneau, look carefully at a closeup shot as Patricia kisses Helen. Parts of each one's hair is inexplicably wet and they haven't been fooling around long enough to sweat.
Continuity mistake: When Charlie goes to jail he sits on the bed and bums a cigarette. Then the next morning he is lying on the bed and bums another cigarette. His bed changes heights in each shot. (01:30:50 - 01:31:25)
Factual error: There is a scene in which the Catholic high school boys are lined up to go to Confession to a priest. One of the minor characters is a compulsive masturbator, a recurring gag in the film. He is trying to estimate how many times he has wanked since his last Confession, and Kevin Dillon's character takes out a digital calculator to help him figure it out. The film is set in 1965, about 8 years before personal calculators hit the market. (I was precisely the age of the characters in 1965, and we would have sold our souls to the devil for such a device. It was still science fiction!).
Continuity mistake: About one hour in, Maerose is sitting at the table talking to her father. Every shot from the front shows her with her right arm across her body, but every shot from the rear shows her arm forward on the table.
Continuity mistake: When Dalton is having his picture taken with his camera by the blonde next to the pool, she has his camera. Christopher confronts him, then in the next shot Dalton now has the camera and the blonde is holding red roses.
Continuity mistake: When the men posing as painters rip off the drug dealers, they place a scaffolding plank to cross to the other building, which they remove from the windows and it falls onto the street. When Chuck Norris enters the apartment it reappears.
Continuity mistake: The judge arrives and tells the audience that they can sit down. The guy on the left with a white linen shirt sits and crosses his left leg. Reverse shot, and he is repeating the action, this time crossing his right. (00:03:20)
Visible crew/equipment: At the end when the helicopter is hovering above the two guys fighting, we see the shadow of the camera on them multiple times.
Character mistake: Morgan Hiller's father is named Stewart (according to the story as well as credits). But in one scene when Morgan and his parents are having dinner, Mrs. Hiller calls him (her husband) "David" one time (instead of Stewart).
Continuity mistake: During the scene when Andrea's talking about suing the club, the amount of papers in her hands change from 4 to 5 in between shots. (00:44:20 - 00:45:21)