In the theatre, Babe is seated directly to Harley's right. However, when Harley throws popcorn at Mario, and again later when he yells at the teens to shut up, that seat is empty.
When Sully goes to sit down, he spills popcorn, but after he sits down, the popcorn is full again.
Even as the killer drags the bloody bodies down the same hallway each time, the floor stays clean.
Det. Barrons tells Bobby that he is going to be sitting the back row. However, when Dr. Wayne arrives, he is obviously several rows in front of the back row.