Factual error: There would be no slide latch on the inside of the pantry that Alice hides in before hitting Mrs. Voorhees with the frying pan. It would be on the outside.
Continuity mistake: Crazy Ralph comes out of the pantry and Alice screams. Marcy and Ned come running into the kitchen. Ned is eating a hamburger that hasn't been cooked until the next scene.





Chosen answer: Just after the credits, there's a bank sign that says "Friday, 13 - 7:01 - 60 Degrees". Then the DJ says "It's 7:01 on Friday the 13th of June." and goes on to say some more about it and lists some other bad luck superstitions. At two other points in the movie, two characters (Ralph and Tierney) say "it's Friday the 13th". So there are at least four references to the fact that the movie takes place on Friday the 13th.
Myridon