The goth girl's skirt disappears and reappears in different angles during the sex scene.
Auntie May first sits on a bench, after arriving in the deserted town, she is then seen sitting in a rocking-chair, during the "...he's so gay..." and the "push & pull-ups" scenes, then she is seen on the bench once more, sat next to the young man with the green & navy-blue stripped t-shirt.
While none of the resurrected serial killers resemble their real life counterparts much the casting of John Wayne Gacy is simply peculiar. The clown make up, facial hair and age are all very far from the real life Gacy.
Several scenes are obvious day for night.
The rooms at the Death Factory are supposed to be exact recreations of the serial killers' lairs. However, Ed Gein's lair contains a modern chainsaw of a type unavailable in 1957.
When Nicole and Candi start making out, Kip looks at his wrist and announces they have an hour before they have to go. He is not wearing a watch.