Other mistake: On the back cover of the DVD it says "An idyllic summer turns into a nightmare of unspeakable terror for yet another group of naive counselors." The cast of this film are Chris's friends, not camp counselors.
Other mistake: After Jason slashes Andy in the hallway we see the machete ripping down through Andy's abdomen as he is upside down in his handstand. Then his body falls to the floor and Jason starts dragging him, but there is no blood spatter anywhere on Andy's chest, face, or the floor.
Other mistake: When Chris finds Shelly "pretending" to be dead, if you look as she opens the door, you will see the door lock on the knob is outside the door, not inside.