Saw IV (2007)

Continuity mistake: The blood stain on Riggs' white shirt around the neck has blood under the collar, then at the end it is over the collar and has increased in amount.

Jigsaw: Hello Brenda. I want to play a game. An officer will try to save you. If he is successful, then your game begins. This man will use these photos to sentence you for your crimes and the only way to stop him is tapped underneath the TV. Let him save your life, and accept your fate to rot in prison, or kill him... and guarentee your freedom. Make your choice.

Trivia: At one point, the producers were considering using a version of the autopsy scene as the final scene in "Saw III." It was then retooled and used as the opening for this film.

Question: A tape recorded by John directed toward agent Perez states that her partner would soon take the life of an innocent man. How did John know that agent Strahm would kill Jeff? For all he knows, Strahm could have followed Rigg through the factory rather than Jeff. The "if you're good at anticipating the human mind, it leaves nothing to chance" excuse doesn't work here. The only reason Strahm followed Jeff was because he heard Jeff hit a ceiling light with a crowbar.