To raise funds, the kids sell advertising space on Slater's jersey. Slater's jersey is shown after the cheerleaders sew the advertising on, however, for the remainder of the show, Slater is wearing his jersey and none of the advertising is present.
Traditionally, homecoming parties are held after - not before - the game and coronation. Also, homecoming is traditionally celebrated on weekends, not during the week.
Everyone (not just Slater) in the Mercedes would likely have some type of injury resulting from the accident.
Everyone in the Mercedes would likely be charged with auto theft.
After driving drunk and having an accident, Zack and Company are sober enough to call for a tow *and* push Dr. Turtle's car into a conveniently-empty garage (don't ask). Just hours later (that morning), the gang is so hung-over they can barely stand on their feet.