Revealing: After Dr. Lawrence cuts off his leg and is crawling towards the gun, if you look at his dismembered leg, you can make out the shape of his foot hidden beneath his ripped up slacks.

Continuity: When Adam pounds on Zep with the toilet seat, he grabs his shoulder in pain. In the first shot of him holding his shoulder, his hand is soaked in blood. In the second shot, however, his hand is much cleaner.

Continuity: When Alison gets the gun from Zep and aims it at him, the gun is in her left hand. In the next shot it's in her right hand, and then it moves back to her left hand again. This is not an artifact of changing camera angles, you can clearly see the different hands holding the gun.

Continuity: When Larry is desperately trying to reach for the cell phone, he uses the box that it came in. When that doesn't work he throws it off to the side (his left) but when we see it again the box is back where it originally was (on his right).

Continuity: When Dr Gordon begins to saw his foot off, the blood seen covering his neck and top disappear in subsequent shots.

Revealing: When Larry notices the clock on the wall, he puts his hand on a pipe. Watch the pipe, it bends in and foams out when he takes his hand off it, revealing it to be made of foam.

Factual error: Dr. Gordon is seen in a close-up to be sawing through his leg, some inches above the ankle joint and the shackle around it. Considering the long bones of the leg (fibula and tibia) are very tough in a young man, it would take a long time to saw through by hand, during which Dr Gordon should have passed out from pain-induced hyperventilation then died from shock.

Factual error: The Swedish subtitlers made Amanda's situation even more tragic, incorrectly translating her dead cellmate as her dead soulmate.

Continuity: When the victims first find the saws and are vigorously trying to cut the chains: The wide angle of Larry sawing, shows him cutting at the chain. Close up he is cutting the padlock.

Continuity: In the scene where. Lawrence and Adam find the 'X' on the wall, there is a continuity error. Right after they find the 'X', the lights are turned on and there is the shape of a square on the wall (the cavity where the box is hidden). Before they find the 'X' there is no box or any dirty lines where the cavity is.

Visible crew/equipment: In the scene when Adam walks around his apartment with his camera (because the lights were out) the filmmakers put lights in the set so the actors wouldn't walk into walls, and also letting the audience see what's actually happening. In the movie, though, there are supposed to be no lights on at all. However, just before Adam opens the closet door with Jigsaw in it, you can see the reflection of one of the set's lights on the top of Adam's camera.

Visible crew/equipment: After the first call when Dr Gordon gets on the cell phone, a boom mike shadow is visible on the bathroom door.

Continuity: When Dr. Gordon gets out of Tapp's car and is talking to him at the car window, the amount of shirt sleeve showing under his jacket changes between shots.

Continuity: When Larry takes the box out of the wall, it turns itself around from when he's holding it, to when it's on the floor (keep an eye on the box's padlock).

Continuity: When Larry looks at the picture with Zep at the window, from one angle the picture is all crumpled but in the first person view, it's smooth. This changes several times.

Revealing: When Adam is searching Zep for the key to the chain once he has found the tape recorder watch Zep's tummy - he's breathing.

Revealing: In Adam's flat just as he starts beating Jigsaw's doll (Billy) up, you can see that he's not actually hitting the proper puppet, but a cheap replica. You can tell by the red lines on it's face, and there is no red marks where it's mouth is.

Audio problem: When Dr. Gordon is dialing 911, we hear one low tone then two higher tones. On touch-tones phones, 1, 4, and 7 are the lowest tones while 3, 6 and 9 are the highest. Gordon would have dialed a 1, 4 or 7 first and then a 3, 6 or 9 twice in succession. Possibly 1-9-9 for Emergency?

Continuity: Adam's hacksaw blade snaps almost as soon as he gets it. However, later on (just after he gets electrocuted) we see it lying beside him with the blade in one piece.

Visible crew/equipment: You can see the shadow of the camera on Dr. Gordon's sleeve when he is talking to Diana sitting on her bed.