Before rappelling of the cliff, Joel switches his yellow and blue Asics for some more appropriate footwear. In the next showing him rappelling of the side of the mountain, he is seen wearing the Asics. In the next scene, he is wearing the hiking boots again.
During the campfire scene, Gail can be heard off camera telling a story about not being able to get out of a car during a flood. Just a few minutes later, she's telling it again. A few minutes later, she's telling it yet again, only this time on camera.
During the first facial closeup of Gail's dead body upon discovery by the park ranger, Gail's carotid artery clearly has a pulse.
The deformed side of Karel Struycken's face switches from right to left to right again.
In the close-up of the dying lantern in Greg's hands (about 38:30), the brim of a hat can be seen in the corner of the frame, but in the long shot Greg is not wearing a hat.
Characters' voices don't match lip movement; numerous instances within the first 5-10 minutes.
The killer's deformed appearance was the result of burns that he received in a fire and is not his original appearance. So, the baby that he had with Nancy would have a normal appearance and she would have no reason to scream.