Continuity mistake: When Erickson is offering full disclosure to Hoffman, Erickson's badge is uncovered. Camera changes and now it's half under his jacket. (00:14:20)
Continuity mistake: When we see Eddie cutting the flesh in the opening game, the amount of blood on his shirt decreases and increases between shots. (00:04:40)
Continuity mistake: At the start when Simone is telling Eddie to wake up he has his hand on his chest. Camera changes and it's not. (00:01:50)
Continuity mistake: Simone wraps the tube round her arm just as the camera does a flash change. When the camera shows Eddie briefly, you can see Simone in the background with her arm on the table and a knife to her elbow. However, less than a second before she was tying the tube. (00:03:50)
Factual error: The license plate on the back of Jill's car does not specify the state. It only has the number listed and "Fairweather State" written at the bottom. While it's never specified what state the Saw films take place in, every U.S. state and Washington D.C. require vehicles to have a state-issued license plate on the rear of the vehicle, so it can't be a vanity plate. (01:00:31)
Audio problem: Simone's scream at the end of her game is the same as one used earlier in the scene. (00:06:00)
Chosen answer: It's possible, but unlikely. 1) She was under great distress and might not have thought of that. 2) It would be easier (and more importantly, quicker) to cut through Easton's soft skin than the spear. 3) There is a good chance that tampering with the spear might have made it go off.
TedStixon