Continuity mistake: When Gibson asks Jill if she knows who the man in the picture is, he is holding the picture in his left hand. When the camera cuts it is now in his right hand. He's also reaching between different bars. (00:48:40)
Continuity mistake: When Bobby is pulling teeth, he gets blood all down his shirt in one shot. Camera does an instant cut and the blood has disappeared. (00:59:20)
Continuity mistake: When Evan is thrown through the windshield of his car, all the glass is removed. When Homicide and IA are examining the car, half the windshield is back. (00:21:00 - 00:27:35)
Continuity mistake: When Bobby is first hearing from Billy The Puppet, his grip on his cage is constantly changing between camera cuts. (00:30:00)
Visible crew/equipment: When the camera is panning down on the mess that is the junk yard, look in the cars and you can see a shadow moving. Clearly the camera. (00:27:30)
Continuity mistake: After Bobby fails to save his publicist, he has a large amount of blood spatter from her on his shirt. In the next scene, however, there is a lot less blood on his shirt, and it's spatter-pattern isn't the same. (00:41:25)
Continuity mistake: Hoffman shoots the cop guarding Jill through the eye and some brain matter appears on the prison bars. Camera changes and the brain matter has disappeared. (01:11:20)
Continuity mistake: When Bobby gets the code for the last door from his teeth, the position of the teeth changes instantly. (01:01:50)
Continuity mistake: When Dr. Gordon looks down at his own severed foot at the end of the film it is laying on the outside of his foot, yet when the foot is seen in Saw 3 it is laying on the inside of the foot. (01:21:10)
Continuity mistake: We are shown Jill posting the video to Dr. Gordon. There is no writing on the envelope, however when it lands, same side up, there is. (01:18:20)
Continuity mistake: In the bar scene the amount of head on the beer and the level of beer changes in the glass without anyone touching it. (00:33:20)
Continuity mistake: In the garage trap there is one shot of the car that Evan crashes into and the windshield is intact. Yet in another angles just before Evans car crashes into it, the windscreen is smashed. (00:21:00)
Continuity mistake: Brad shoves the saw blade into Ryan's face in the public trap. Ryan dodges out of the way, camera does an instant cut and he dodges the saw again. (00:05:25)
Other mistake: Bobby extracts 2 teeth forcibly to get into the final room, however when he's in the other room his mouth is no longer bleeding. The blood wouldn't stop that quickly. (01:02:15 - 01:10:00)
Revealing mistake: During Jill's dream where she is killed by the "Death-Kart", watch closely. During at least two shots, you can see wires near the wheels that are pulling the cart, revealing it isn't self-propelled as depicted. (They are visible in the third shot of it moving forward, where the camera moves upwards and tilts down, and in the sixth shot of the moving cart, where the camera is looking down). (00:17:40)
Revealing mistake: When Bobby's wife is dragged to her knees by the chain, you can make out the shape of her knee pads under her trousers. (00:41:10)
Visible crew/equipment: The second time Gibson looks round the room where the Reverse Bear Trap was found, look in the mirror and you can make out a camera man. (01:02:25)
Continuity mistake: When we see Cale's trap, he has got sweat stains on his shirt, in the shot from the floor, there is no sweat stains on his shirt. (00:50:30)
Revealing mistake: When Gibson is explaining how Hoffman saved his life, in the flashback he closes his eyes and braces for the bottle attack before it arrives. (00:55:20)
Visible crew/equipment: When Bobby is walking to his car there is a very nice reflection of a stage light visible in his car. (00:26:30)
Answer: He, his wife and his daughter were abducted before he decided to work with Jigsaw. He didn't put them in danger. As for why he decided to work with Jigsaw following his ordeal, like other characters in the franchise, he either developed a level of Stockholm syndrome or he concluded that Jigsaw's methods were right, or a combination of both.
Phaneron ★