Other mistake: In the Disciplinary/Probation Hearing scene, the State Flag behind the Council is that of Tennessee. On the Double Secret probabtion edition, narrator John Landis says "Faber College in Pennsylvania". (01:01:00 - 01:06:00)
Other mistake: When Pinto throws rocks at the mayor's daughter's window, the first two rocks bounce off the window and don't get her attention. The third rock supposedly breaks the window. If you watch closely, you'll see the rock bounce off the window while a glass breaking sound is heard. Likewise, when the mayor's daughter opens the window, it is intact.