Plot hole: Det. Kerry says at the scene of Paul's trap, "He had two hours." There is no way she could have known that. The clock simply said 3:00 and the tape specifically says "you have until 3 o'clock or this room will become your tomb". No way to know that's two hours after the fact. (00:17:30)
Revealing mistake: 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. (01:29:30)
Continuity mistake: When Dr. Gordon picks up his tape, the way he holds it changes instantly. (00:06:50)
Continuity mistake: 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. (01:20:30)
Continuity mistake: 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. (01:30:25)
Visible crew/equipment: In the scene where 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. (01:07:40)
Factual error: The Swedish subtitlers made Amanda's situation even more tragic, incorrectly translating her dead cellmate as her dead soulmate. (00:24:40)
Continuity mistake: 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). (01:25:40)
Revealing mistake: When Adam is searching Zep for the key to the chain once he has found the tape recorder watch Zep's stomach - he's breathing. (01:32:15)
Factual error: While Dr. Gordon is sawing off his foot, he only has blood on his hands and some on his shirt. Since the blood on his shirt was from splatter, that means he must have cut through a few veins or arteries, yet he has no blood on his arms or face, which should certainly happen when cutting through something like that. (01:26:30)
Continuity mistake: 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. (00:14:30 - 01:03:30)
Plot hole: Jigsaw is lying on the ground with a gun in one hand, and a tape recorder in the other; the tape recorder is removed, leaving his hand empty. If both of his hands were occupied/exposed, he would have had no way of depressing the button on the remote control to shock the prisoners. As seen at the end, when he shocks Adam the final time, the control is in his hand, not hidden anywhere else on his body.
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. (00:10:00)
Continuity mistake: When Dr Gordon begins to saw his foot off, the blood seen covering his neck and top disappear in subsequent shots. (01:26:40)
Continuity mistake: 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. (00:14:20)
Continuity mistake: 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). (00:54:50)
Revealing mistake: 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. (01:07:30)
Continuity mistake: 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. (00:54:00)
Continuity mistake: 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. (01:18:40)
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. (00:34:20)
Suggested correction: In the flashback of the razor wire trap, it shows the clock as a few minutes past 1, so he did know he had 2 hours.
Paul knew he had 2 hours as like you said he could see a clock counting. But how did detective Kerry who made the remarks in the first place as listed in the mistake?