Continuity mistake: After the pizza man is discovered dead, Kim puts the phone down on the desk before running into the living room. While Coach Jana waits on the line, it goes dead. In the next shot, Trish picks up the phone and speaks to an operator just before Russ Thorn cuts the phone line.
Continuity mistake: When Russ Thorn chases Linda down the corridor, she runs right to the end of the corridor, then heads down the last row of lockers, and Russ follows her (there is also no poster on the wall.) In the next shot of Russ running down this row of lockers, it's now apparant that it's not the end row; because there is no end wall, and now there is also a poster on the wall behind him.