Continuity mistake: When Mr. Hand shows up at Jeff's house to study history, the bong in Jeff's bedroom alternates between full of smoke and empty. (01:15:15)
Continuity mistake: When Brad admits to his boss he threatened his customer, Brad is shown and there's nothing out the window behind him. Brad is told he's fired (instantly) and then Brad's shown again (only one second later from same exact position) with a potato chip truck sitting still out the same window. There's no way a truck could just appear out of nowhere in only one second-slowing down to a stop maybe, but not sitting still that quickly.
Continuity mistake: When Mr. Hand writes his name on the board to introduce himself to the class, he underlines it. The underline changes a few shots later, and then the lines revert back to the way they were originally. (00:09:30)
Continuity mistake: When the word prick is painted on the gremlin door, the top of the k is painted on the door handle. When the car pulls into the parking lot at school with the cardboard covering up the writing, there is no paint on the door handle.
Continuity mistake: When Mike is trying to get Mark to ask Stacey out, there is a shot of her behind the counter and Stacey's hair is pulled back on the sides in french braids with ribbons on the ends. Then when Mark approaches Stacey, her hair is pulled back in a clip. The first shot of Stacey with the braid, is actually cut from a scene later in the film, when Mark and Stacey talk at the counter. (00:27:35 - 00:28:20)
Continuity mistake: After the Last Dance scene, they show a night shot again like in the very beginning of the movie of people coming and going at the mall. If you look closely, you can tell this was shot the same night the beginning scene was filmed. For instance, the guy in the grey blazer and black pants is there again, but what gives it away most is the woman on the far left in the red and white Hawaiian dress, she even is in her same spot as the scene at the start. (01:21:00)
Continuity mistake: In the restaurant (of Mark and Stacy's date), the upper cabinets in the back by the left corner of the screen are not covered by curtains. Then when Damone comes in and gives Mark the wallet, the same cabinets are now covered. Then seconds later as Mark and Stacy start leaving, they are uncovered again.
Continuity mistake: When Rat approaches Stacy at the check-out to ask for her phone number, the characters in the background keep changing. Sometimes you see Damone standing there; other times there are different people.