Is this one of the first examples...
...of the teleporting killer in slasher films? Let's see (spoilers!)
The slutty girl (was it Lisa? I'm horrible with character names) is waiting in the dark for the professor when she hears SOMEONE come through the door. Since the professor never shows, I assumed we were meant to think it was the killer. Then we cut to Radish running to Courtney's room, only to find the killer waiting for him there. Courtney discovers his body, and then the killer shuts her door from the inside, kicking off the chase scene. But we never see him come out of her room, and in the next scene he shows up in the art room to off Lisa.
Maybe we weren't meant to think the killer was still in Courtney's room, but the way the door shuts and they actress's reaction to it made me feel that way.
Future posts such as these will affect you in the future!