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.
Audio problem: After Spicoli crashes Jefferson's car, Jefferson's brother says "My brother's gonna kill us - he's gonna kill us" yet his mouth isn't moving during those lines (even though shown from the back you can still tell). Then camera faces him and he now matches the words.
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: As a teacher myself, you learn to be able to recognize "problem" students fairly quickly (those that are going to be disruptive, late, etc on a regular basis). Mr. Hand is simply overly strict in regards to Spicoli unexcused tardy and seems not to allow students into class late, thus earning the student an absent. Mr. Hand does say he "will make you" attend his class. In addition, Spicoli was high and, in Mr. Hand's mind, disrespectful (Spicoli said "hey I know that kid" while they were talking) so Mr. Hand showed Spicoli disrespect in return as a way to teach him a lesson.
Bishop73