Plot hole: When Rigg is listening to the tape in the first hotel room, the tape instructs him to wear the pig mask in order to conceal his identity from the hotel cameras. Rigg wasn't wearing the mask when he entered the hotel, so putting the mask on after the cameras have already seen his face would do absolutely nothing to conceal his identity. (00:36:00)
Saw IV (2007)
2 plot holes - chronological order
Directed by: Darren Lynn Bousman
Starring: Tobin Bell, Betsy Russell, Costas Mandylor, Scott Gordon-Patterson, Scott Patterson
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.
More trivia for Saw IV
Question: A glass casket with a key inside it is shown in John's warehouse. What does that mean?
Answer: This was revealed by director Darren Bousman to have originally been used in a now-deleted (and not released as of Oct. 2020) scene in the movie. The glass box is used for what is (most likely) a different purpose in Saw V.
Answer: It plays an important role in the next few movies.