Continuity mistake: After Xavier kills Jonas with the spiked baseball bat, we see Amanda, Daniel, Addison and Laura in a hallway. Laura collapses to the ground due to the nerve gas that they've all been inhaling. Between shots her left arm moves from her stomach to across her right shoulder. (01:02:00)
Revealing mistake: When Obi is getting burned, you can sometimes see the end of the oven at the side, for where the camera can see inside it. (00:41:20)
Continuity mistake: The way Daniel holds the picture of him and his dad changes instantly. (01:01:25)
Visible crew/equipment: When Alison is in the hand box trap, if you look very carefully you can see a boom mic arm reflected in the glass in one of the quicker shots. No Slow-mo required. (01:07:00)
Continuity mistake: Eric sits down after finds out who is in the game with Daniel. When he does, the walkie-talkie on the desk simply disappears between different shots. (00:56:40)
Continuity mistake: In the office when Detective Matthews and Kerry are arguing, Matthews' gun keeps changing position on the desk with no-one touching it. (00:09:10)
Continuity mistake: At the end when Det Mathews is in the same room as Saw 1, you can see the mirrors on the wall. Both are intact, when one of them was broken by Daniel in the first movie.
Continuity mistake: After Xavier's had his throat cut, he grabs Daniel's shirt and his hand is completely covered in blood. The camera cuts away and then cuts back, and suddenly his hand is bone dry. (01:15:30)
Continuity mistake: When we see the SWAT team aim their lasers on Jigsaw, we see several dots. A few officers move and 2 remain. However we still see 5 or 6 dots. (00:15:00)
Continuity mistake: The tape on the picture that Daniel has keeps changing. In some shots it's all nice and neat; in others it's curled up and taped to itself. (01:02:30)
Continuity mistake: Right after the guy gets shot through the door, it goes back to detective Matthew, and there is a small cut above his right eye. In the next shot it's above his left eye, then back. Meaning the shot is backwards. (00:25:10)
Continuity mistake: Jonas is listening to the tape again. When the door opens, the tape stops playing. But you don't see Jonas stop the tape, and there is more left on the tape as we have heard it before. (00:26:20)
Continuity mistake: When the people spot the envelope with Obi's name on it, the blade of the knife holding the envelope changes angle between shots. It goes from vertical to horizontal. (00:34:15)
Continuity mistake: The way Kerry is holding the files of the people in the game changes instantly when Matthews grabs the files from her. (00:56:25)
Continuity mistake: In the scene when Eric Mathews goes to confront Jigsaw (after he first looks at the monitors), the chain of his badge gets twisted when he gets held back, but as he's about to leave the chain appears, untwisted. But when he gets back to the monitors, his chain is twisted only to be untwisted by him a few seconds later. (00:16:30)
Factual error: After falling into the pit of needles, somehow all of the needles in Amanda's skin stay intact and do not break, despite her fall and her rapid digging through them. Very, very unlikely at best. (00:50:50)
Continuity mistake: Right at the end, the amount of blood and cuts on Jigsaw's face changes when he is in the van with Det. Matthews. (01:10:30)
Continuity mistake: The position of Det. Matthews' cigarette in the ashtray changes when he's arguing with Det. Kerry about her being the "Jigsaw expert." (00:09:45)
Continuity mistake: When Det. Matthews leaves Michael's crime scene, just before Kerry says, "Look closer, Det. Matthews," his tie changes position between shots. Note the position of the knot. (00:08:20)
Answer: It was Zep, but he died because Adam smashed his head with a toilet seat cover.