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)
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: 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)
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: 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 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: 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.
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)
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: In the beginning when they're all showing up for school Eric Stoltz is putting his skateboard in his locker. A couple of minutes later he and his friends are getting out of the van with his skateboard.
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.
Answer: From what I can gather, "So Much in Love" by Timothy B. Schmit was in the original release of the film, but due to licensing rights issues, home video and cable TV versions of the film replaced this and two or three other tracks. For the 1999 DVD release, the rights seem to have been renewed and the soundtrack matches the original theatrical release.