Continuity mistake: Brenda is seen swimming really far out to rescue Ned, and Marcie rows her boat out to the middle of the lake, yet when they rescue Ned, they are right beside the white decking. (00:23:15)
Continuity mistake: In the shop Annie enters, the tissue dispenser and boxes move much further away from Enos between shots. (00:08:05)
Continuity mistake: When Claudette and the counsellers are singing in the beginning, the close-ups of Claudette show her legs crossed, but the far-away shots show her legs spread apart. (00:02:10)
Continuity mistake: When Annie goes over to the dog and stops to talk to it, in the first shot the dog is in the sun, yet in the next shot it is completely shaded. (00:06:50)
Continuity mistake: The trees and scenery around and behind the truck, as we first see Ned, Bill and Marcie, changes bewteen closeups and wideshots. (00:12:00)
Continuity mistake: When Alice runs to the beach, there is only one canoe sitting there. But when she finally gets in the canoe and pushes off, there are two. (01:23:10 - 01:25:15)
Continuity mistake: After the sheriff gets the call over his radio, he turns on his red lights. In the next shot they are off again, and are then turned on once again. (01:00:25)
Continuity mistake: First Bill and Alice are looking under the bed for the snake. In the next shot Alice is not the one looking under the bed, but she is kneeling behind Marcie, who now is looking under the bed with Bill. (00:25:35)
Other mistake: When Ralph is leaving on his bike he passes the same rock twice.
Continuity mistake: When they see the snake in the cabin they all jumps after it under the bed in panic. But in the next shot from under the bed you see them calmly lifting the sheet on the bed to look under it. (00:25:25)
Continuity mistake: When Steve's car won't start you see a police car pull over. The sheriff turns on its red lights and Steve goes towards it and opens the door. In the next shot you see him talking to the sheriff, but now the lights are off, it cuts again and the lights are on. (00:50:30)
Continuity mistake: When Annie gets into the bar and asks about Camp Crystal Lake, you can see the woman behind the counter standing leaning in at the end of it. Then two cuts later she turns around, suddenly standing by the cashier. (00:07:40)
Continuity mistake: Just before Annie jumps out of the van, the truck is turning a bend. When the truck stops and backs up, the road is straight. It's a clearly new road. Also, the trees and leaves along the ditch have changed. (00:19:55)
Continuity mistake: When Alice runs to the lake to Bill she says "Bill, Steve wants to know if you need more paint", while holding her arm to her hip. When it cuts her arm is down. (00:16:20)
Other mistake: After Alice wakes up in the hospital, watch the nurse after she gives Alice the injection. Her eyes, at one point, look directly into the camera. (01:27:45)
Visible crew/equipment: At the diner, when Sandy walks to the other end of the counter and talks to Steve, the reflection of the boom mic is visible at the top of the window behind Steve. (00:48:10)
Continuity mistake: When Ned fakes drowning he is a decent distance from the dock. When he is rescued he is much closer.
Factual error: When Jack and Marcy are sitting by the lake talking, a storm starts. At one point, lightning flashes "yellow" in their faces. Lightning does not flash yellow.
Continuity mistake: When Alice wakes up she has white socks on. When she walks to the kitchen they are black. (01:08:00)
Character mistake: When Annie is in the red truck, she says that she'll be cooking for ten staff. When Alice goes to the beach, she tells Bill that everyone has arrived except for Annie. Even if she had arrived, there would only be eight of them: Christie, Annie, Ned, Brenda, Jack, Marcy, Bill, and Alice. Two shy of what she told the truck driver.
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