Other mistake: In the aerial shots of the semis being driven in the mall parking lot, the zombies are milling about. Notice they have left a path just clear enough for the truck. (01:02:40)
Other mistake: When the gang are at The Palimino Club, there are certain long shots you can see that there is no roof to the room and it's a 3 sided set.
Other mistake: When Superman and Lois are flying through the clouds, there are a number of shots in which we see Superman from Lois' point of view. If you look closely, you can see that Christopher Reeve is not being suspended in these shots, but is, in fact, kneeling to look as though he is flying. You can tell by the profile of the red trunks.
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 the bad guys are taking the cash from the vault, they finish with just 3 duffel bags. Yet there are blocks of cash along all the walls, roughly 25 times as big as what they're taking. With the duffel bags supposedly containing $100 million, there would be tens of billions of dollars for the taking. Their escape route is up the elevator to the roof, and into a helicopter. What bad guys wouldn't take all they could carry?DavidRTurner