When Jerry is in class and the teacher is scrolling through the names of the students on her clip-board. If you look at her fingers while she is seen holding the clip-board, she has nice, painted, long fingernails, when they do a close up of her running her finger down the list of names you can clearly tell it's a guys finger with a short non painted fingernail.
The calendar in the student store advances 2 months within a 3-hour period. At the beginning of the film, when Jerry is talking to his sister, the calendar is on October. Later, when Franny meets Jerry in the store, you can see that it is now December. It's still December at the very end as Miss Farmer walks out.
During the opening credits, as Jerry is driving to Franny's house, there is a shot of Franny picking up some text books off of a table. Upon close inspection, the ink stamp on the side of one of the books says "Ogden High School". This is the name of the school where the film was made, not where it takes place.
During the opening credits, when Jerry is driving to school, at 5:15 he narrowly misses a red Peugeot 505 and a blue Plymouth Reliant at an intersection. At 6:45 when he goes through the red light intersection, the same cars are used for the cross-section stunt.
After Buddy punches Craig in the library and the bookcases topple he holds up a bloody finger. However it was Buddy who broke Craig's finger and Buddy's finger would not be dripping blood from his one punch to Craig's face.
When the football player goes to beat Buddy up in the library (after Jerry had paid him to do so), he pokes Buddy's chest with his index finger. When his finger presses on Buddy's shirt you can see the outline of Buddy's mic/equip.