Other mistake: In the original ending, after Laurie is pulled out of the cop car, Loomis is able to reason with Michael to let her go. After he does, he is shot to death by the police. This was obviously changed, but when Loomis is reasoning with him in the final cut, you can still see the police standing behind him. (01:46:00)
Other mistake: In Saw II, Jigsaw shares a story with Detective Matthews about how he attempted suicide after his cancer diagnosis by driving his car off a cliff. We then see Jigsaw pulling a metal rod out of the left side of his stomach. However, no puncture wound/scarring is visible on Jigsaw's stomach when his autopsy is being performed. (00:00:50)
Other mistake: In the scene where Dr. Isaacs is in the teleconference with the Umbrella Board of Directors, there are several glasses of water sitting in front of each individual hologram. At the end of the teleconference, the holograms of the board members disappear, but none of the glasses follow suit. This tells us that the glasses of water were physically in the room with Dr. Isaacs, for absolutely no reason, given all the other attendees weren't really there. (00:17:40)
Other mistake: When the bunch of soldiers find Dr. Paul Foster, one of them removes the doctor's briefcase from the crack in his skull. In this scene, Foster's eyes are open and seem to be red. Before and after this scene, when you can see the eyes, they are clear white. The briefcase doesn't have any trace of blood on it, though it was in the bloody skull crack. The blood looks too reddish. If it is some hours old, it should look darker. (00:34:10)
Other mistake: Towards the end of the film, as the two kids are escaping through the subway being guided through the night vision scope used by the army major, they are virtually blind and have to pick their way through dead bodies, escalators etc. This seems a bit unnecessary as the M4 rifle to which the night vision scope is attached also has a torch attached to the RIS rail. Military spec torches are extremely bright - why not just turn it on? They can't be worried about being spotted, because they are shouting at each other, not concerned with what might spot them.
Other mistake: It is said Jamie has no alibi in the beginning scenes of the movie, and the detective immediately drills into him as if he committed the murder. Yet Jamie did have an alibi, he was out getting Chinese food and had it been checked out with the restaurant. No reason for Jamie to prove his innocence. (00:10:00)