New this month Revealing mistake: At the beginning when the coroner cuts the bucket off the body, the metal is red hot and her pinky touches it. Not only does it not burn the glove but it doesn't burn her.
New this month Other mistake: When Mitch is getting the tape for Ryan when his leg is trapped, we see the wires get tighter and snap the rake handle when touched slightly. As Mitch is bringing the player up from in the wires, he touches a couple of the wires but there is no reaction from the mechanism.
Plot hole: Spoilers. It's revealed that the barn game takes place at an old farmhouse owned by the family of Jill Tuck - Jigsaw's widow. It's public knowledge that she was married to Jigsaw and that buildings they owned served as the headquarters of several past traps, so the barn should have been investigated at some point in the meantime. Ten years have passed. It makes no sense that the barn was never investigated and that the bodies of the barn victims were never discovered.
Revealing mistake: During the opening trap, at one point one of the five "Bucket Heads" starts banging on the wall behind them. If you look very closely, you can see the set-wall waver slightly as it's struck, revealing it's not really a concrete wall. (And it's not supposed to be the doorway that is later revealed during the final twist. It's a separate section of wall).
Audio problem: When Halloran and Hunt are discussing orders from the commissioner to exhume Jigsaw, it's clear that several of Halloran's lines have been looped in post. His voice is a bit too loud and a bit more forceful than he appears to be speaking, and at least one word doesn't quite line up with his mouth movements. It can be hard to spot the first time, but if you look for it, it's noticeable.
Other mistake: During the opening trap we see Mitch strike the blades with his chain and get yanked forward. However, despite being yanked forward he still manages to stand in line with the others which he shouldn't be able to do, as his chain was shorter due to the extra tug he received.