Factual error: The Swedish subtitlers made Amanda's situation even more tragic, incorrectly translating her dead cellmate as her dead soulmate. (00:24:40)
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)
Factual error: After the doctor speaks on the cell phone for the first time and the line goes dead, there is a dial tone. There is no dial tone on a cell phone. (01:09:30)
Answer: Amanda was supposed to put the key around Adam's neck rather than just on his chest. If she had done so as instructed by Jigsaw, he would've been able to unlock his shackle and leave the bathroom. Adam was a voyeur, the irony being that if his key had been placed correctly around his neck, all he would've had to do would be to look around to find it. Adam's tape states, "what do voyeurs see when they look into the mirror, " so, again, it's a hint that all Adam would've had to do was look at himself. I noticed as well, Jigsaw says, "the key to that chain is in the bathtub." /IS/ in the bathtub. Not /was/. So Jigsaw probably thought Adam could still get out. He says, "so many people are ungrateful to be alive. But not you. Not anymore." So it's like, 'I have taught you this lesson, now you can go free because now you'll appreciate your life unlike you did before'.