If Jessica is killed in Chapter 4 -
In the end credits, Jessica is shown screaming and falling down the mineshaft, but the wendigo have already removed her jaw.
If you manage to keep everyone alive and Sam and Mike reach the area where any deceased characters bodies would hang if they had died earlier, there will only be one body visible (the Stranger). Yet Sam and Mike will exclaim that there are "lots of bodies" and will react accordingly.
Chris was the only character, besides Josh himself, that had no part in the prank the gang placed on Hannah resulting in her and Beth's death, as he was passed out drunk at the time. However, Josh chooses to torture him the most with the two 'who lives and who dies' traps. If Josh wanted revenge, surely Mike would have been a more suitable target.
After Emily and Matt radio for rescue in the fire tower, the ranger tells them a helicopter will come at dawn. However if both of these characters die before making it back to the lodge, the rest of the group talk will about the helicopter, even though they have no way of knowing that help is coming.
When Chris chooses between saving Josh or saving Ashley, the two of them are only tied by their hands with their legs completely free. If this situation had not been rigged, the person who Chris didn't opt to save could have held on to their bindings and pulled their legs up above the spinning saw to save themselves.
Chris says that the cable car station has to be locked because strangers have been around and one was found sleeping inside. However, around back there is a shooting range with guns sitting in the open unattended and there is no concern for this.