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.
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.
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.
The goof item below may give away important plot points.
If you kill everyone at the earliest possible moment, in chapter 9, you close the grate to go find Josh with Ashley and Sam going along the tunnels, and Mike still at the sanatorium. If Ashley dies investigating the voice, Sam will not notice and carry on. After reuniting with Mike, they will open a door which shows the bodies of all their friends (including Ashley's) hanging up. At this point, Sam will still split up from Josh and Mike 'to tell the others we're okay' despite them all knowing that they're the only ones left alive.