Factual error: If we are to assume the film is in chronological order over the course of a single school year, then why does the football scene come after Christmas has occurred? High school football season ends well before the holiday season. (00:47:00)
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)
Other mistake: When Spicoli supposedly takes a bong hit, you can see that he only inhales the air from the chamber - he takes his mouth away before the smoke gets to the top of the bong. (01:14:30)
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.
Other mistake: Rattner and DiMone are game planning about Rattner's date with Stacy (Leigh). DiMone tells Rattner that all he needs to do to score with Stacy is play songs from side 1 of "Led Zeppelin IV" (Zoso). You then hear the song "Kashmere", which is on the album "Physical Graffiti".
Visible crew/equipment: When Brad and Stacey pull up in front of the bowling alley and Stacy opens her car door, several crew members can be seen reflected in her car door's window. (01:05:50)
Character mistake: In history class, Mr. Hand tells the students that the Platt Amendment was an amendment to the U.S. Constitution passed in 1906. In fact, it was a rider attached to the Army Appropriations Act of 1901. (00:23:05)
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)
Other mistake: In the scene when Mark Ratner asks for Stacy's phone number, there is a customer paying for a slice of pizza. Stacy tells the customer to pay $1.10. The customer gives her a dollar and change. She then gives him five cents back. The only way this could be right is if the customer gave her $1.15. If he could do that, why not the exact $1.10?