Revealing mistake: When Julie is trapped in the bathroom with the "ghost girl" she is saved when some other girls come in and switch on the lights. However, if you watch the girl who flicks the light switches you can see the switches are already in the "on" position (pointed upwards) and she simply mimes flicking them up. (00:26:47)
Continuity mistake: Throughout the scene when Dane, Lucas and Julie meet Creepy Carl for the first time, Carl is wearing a red diamond-shaped pendant on a chain around his neck, which is sometimes tucked under his shirt and sometimes hanging over it, depending on the shot. (00:44:26)
Continuity mistake: When Susan accidentally surprises Dane, Lucas and Julie while they are armoured up and asleep in the basement, the helmets worn by Lucas and Julie disappear between shots. (00:36:47)