When Whitney and Mike discover Mrs. Voorhees' head, the door slams shut. Why? Jason was below them, and it didn't seem windy enough to slam it. If you slow-mo the scene you can clearly see nobody is by the door.
In the beginning it says "June 13th 1980". After the opening it says present day, which would be 2009. Later around the campfire Wade says that the Camp was closed down "like, 20 years ago" it would be almost 30 years, not 20.
Where did the boat go after Chelsea is killed? We can't see it or hear it any longer.
When Richie and Amanda are having sex, the inside of the tent looks pretty dark, but when we see the tent from outside, it looks very well lit.
In the beginning Richie says "If we were near it, we'd smell it" which is true, but doesn't apply later when Wade is peeing on it, he obviously cannot smell it.
Whitney has been Jason's prisoner for six weeks but she appears too clean for 6 weeks to pass. Was Jason cleaning her? Probably not. Did he feed her?
Jason seems to JUST notice the necklace on Whitney. If she's been his prisoner for six weeks he should have seen it before then.
Shouldn't the sleeping bag have gone up in flames rather quickly? Its still a full sized sleeping bag by the time Whitney discovers it.
When Chewie goes to drink out of the shoe, the opening is facing away from him. When the shot changes just as he says "pussies" the shoe opening is now facing him.
Since 1949 it has been illegal to pump your own gas in New Jersey, therefore Nolen shouldn't have been pumping. There should have been an attendant there to pump it.
As Clay is walking out of Trent's house with Jenna, his saddlebag is over his shoulder. Jenna asks where his car is, and the shot changes. He's now holding the bag by its strap in the other hand. When they get to the motorcycle, he lifts the bag up. In the next shot she says "This thing runs" and again the bag switches spots.
When Bree is telling Chewie how to drink the flaming shot the shot changes from a side angle to behind Chewie. When the camera is behind him, the flame is no longer on the shot glass, but with the side angle the flame is there.
When Chewie is outside in the shed drinking alcohol, the bottle changes from hand to hand WHILE he's drinking, then when he's done drinking its in his other hand again.
While Trent and Bree are having sex she is using a camera to record it, but she puts it down. When Jenna comes knocking at the door, Bree has both hands on Trent, but in the next shot she is filming again.
Again, during the sex scene Bree's hands change position. She has her hands on top of her head yelling "I'm close" the shot changes, and her hands are on Trent, the shot changes again and her hands are back on top of her head.
When Chewie is killed it appears that the screwdriver has moved a little when the scene changes shots.
During the campfire scene it appears that the fire is reflected in Wades glasses...or is it? As Richie begins to say "How's that beer treating you" you can see what appears to be two big lights reflected in Wades glasses.
Since 2004, in New Jersey, the MVC no longer issues registration decals that adhere to the upper right-hand corner of license plates on passenger vehicles. Decals are still issued for motorcycles and commercial vehicles. Customers with passenger vehicles may remove the decals from their license plates, as long as the license plate is not damaged. But there is a 2008 sticker on Trent's vehicle. We can see this clearly when Chewie closes the door and we see the missing flyer attached.
The windshield seems to break like common window glass, not windshield glass.
Jason's head get's sliced off, and he's stabbed in the chest (in addition to the stab wound in his leg), his mouth is also spewing blood. How does he come back to pull Whitney into the lake? And his head looks perfectly fine.
Kat's Explanation: The ending where Jason jumps out and grabs Whitney is a dream.
Clay calls the police when they get back to Trent's house. He says "Yeah, I'm at a house by Crystal Lake. Its...(pause) Yeah. That's it. Hurry." First of all, the house is clearly ON Crystal Lake. Second, its assumed they repeat the address back to him in that pause. He probably doesn't know the correct address, and if he did happen to see it earlier, did he remember it then?