Continuity mistake: In the scene where Charlize Theron and Christina Ricci are in the car and Christina is driving, the camera pans to Charlize smoking a cigarette. The first shot it is half way done, the 2nd time it is at the filter and then again half way done and then it's gone and she lights a brand new one.
Character mistake: When Selby goes out to meet friends, they talk about going to "Fun World" in Orlando. However, they did not actually visit "Fun World" they went to "Fun Spot" (look at the signs on the ferris wheel and behind the carousel). "Fun World" is another amusement midway in Sanford, FL about 30 minutes away.
Continuity mistake: Just after they have trashed the red car, Lee and Selby go into the bedroom of the motel and Selby sits on the bed. Lee opens the wardrobe and then starts talking to Selby. If you look closely, you can see the door she opened is sometimes fully open, half open or closed, especially as there seems to be a metallic rack on the inside of it which makes it quite obvious when it's open.
Continuity mistake: When the red Pontiac Grand Am crashes, the car changes model. The red Grand Am they are riding in before they get to the crash scene is a 1992-1995 model (1996s got a facelift). During and after the crash scene, it is a 1989-1991 model. Prior to 1989 the front end was more squared off and the back end was different (1985-1988's had red rear turn signals instead of amber and the license plate was mounted between the taillights, not down below the bumper as it is on 1989-1991's).
Factual error: Aileen and Selby crash a red Pontiac Grand Am. Although the Grand Am has been around since the mid-80s, the line has had significant changes in its appearance throughout the years (most noticeably with the front hood vents). The movie is set in the late 80s, but the wrecked Grand Am is very a mid-90s' model.
Continuity mistake: As they crash the Grand Am, they narrowly miss a blue and a red flag on the right side of the car, leaving them standing. While outside the car, you can see one of each on the ground on the left side of the car. When they drive away, you can see another blue one on the ground.
Revealing mistake: How on Earth can Selby get those skin tight T-shirts over that huge cast on her arm? They cannot possibly stretch any more than they already are - look at the scene where she and Eileen are checking the mail. There is no way that sleeve would fit over the cast without ripping! It is well beyond the capacity of that tight T-shirt to stretch to that extent! Obviously Christina Ricci had the cast fitted after she was in costume.