Revealing mistake: When McLovin' is in the car with the police, if you look really closely through the reflection from their glasses, you can see the green screen that is used in movies. When the scene shows the outside of the car, there is nothing around them that would reflect the screen.
Continuity mistake: In the scene right before Seth gets backed into by a car, there's a neon 'open' sign in the store behind him that keeps turning on and off from shot to shot. It changes from 'open' to unlit about 3 times, and you can still see the sign when it's unlit.
Continuity mistake: As a police officer begins to pound on the steering wheel of his cruiser he is wearing glasses, when done pounding his glasses are no longer present. When he gets out of the car to question the boys the glasses have returned.
Continuity mistake: When Seth and Evan are turning the corner and are stopped by Jesse when he is about to tell them that they're not invited to a party he's holding, Evan has a drink in his left hand when he turns around, and in the next shot he's holding it in his right hand.