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)
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 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: You see the same shots of Sean Penn driving Forest Whitaker's car on the sidewalk and weaving between the same two cars over and over before he wrecks it. (00:44:00)
Continuity mistake: When Jeff Spicoli says, "People on ludes should not drive", you can see a Honda/Kawasaki dealership through his driver's side window. Six seconds later the car is shown from the outside and he passes by the same dealership again. (00:44:00)
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: During the pool scene, just before the two guys come over, the color of the bra on the girl who is lying on her back changes from darker red to almost orange during different angles. (00:48:55)
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)
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 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: 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: When Brad Hamilton is pouring the coffee in the machine at the Mi-T-Mart, there is a clock on the wall next to the battery display, but when the guy comes in to rob the place, the clock is gone and there is a Hostess Fruit Pie poster there now. (01:23:00)
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".
Suggested correction: Damone (not DiMone), told Rat that when they were making out to put on side 1 of Led Zeppelin IV. The fact that Rat is playing Kashmir from Physical Graffiti is just to show that Rat was unclear about Damone's instructions.
Not sure if Rat is unclear about Damone's instructions... he said he had 4 steps to making sure that getting a date with Stacy and keeping her around, and if all else fails, to play side one of LZ-IV... seems that Rat would (should) have asked if he was unclear then at that point considering Rat had a crush on her throughout the movie. I think that it's more of a musical inside joke if anyone was/is familiar with the Zep catalog realizing two things - one, the first four steps of Damone's plan didn't work being that his character was pretty shady and fake (off camera...because you don't see Rat implementing any of them) and two, that "he can't even get the music correct" due to his nervousness.
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: 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?
Suggested correction: In this scene, when Stacy says "$1.10, and you get 5 cents back", the price is actually $1.05 and the customer gives her $1.10 and she gives him his change, which would be 5 cents. When she says "$1.10", she was only confirming the amount the customer gave to her, not how much she wanted from him.
Pause the movie. The total on the register is $1.10 then it shows .05 change. The guy paid $1.15.
Who does that? - who pays an extra nickel just to get the same nickel back? Normally when a person overpays (and this is "normally") the cashier usually says "oops - you gave me too much."
Suggested correction: She types in what the customer gives her and the register gives the change amount back. The total bill was 1.05, not 1.10.
The register show $1.10 (as well as $0.05) before he gives her any money.
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.
Character mistake: Damone claims he made a $16 profit by selling the two scalped Van Halen tickets; since he sold the tickets at $20 each when they originally cost $12.50, he actually made a $15 profit.
Other mistake: Football game ends 42-0, but it's only in the 2nd quarter according to the scoreboard.
Plot hole: In the very beginning at the mall, where the older guy comes in to the pizza shop and sits in Stacy's section - the co-worker says "she's not even in high school yet." First of all, the school she's at is "Ridgemont High", and secondly, if she wasn't in high school (which would mean she would be younger than 15 at least) - how could she have a job, where the minimum age is at least 15? Even by mall standards, it's doubtful they would hire someone who is 14.
Suggested correction: In the 80s, high schools in most California areas were 10th through 12th grade (not 9th-12th like they are today). So many students DID enter high school then at 15.
Continuity mistake: When the Santa sits down in the Pizza place after getting urinated on, when his food is brought over his fake mustache is covering his mouth because it's so big, then a second later when he is shown again, the mustache is suddenly smaller and you can see his mouth.
