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
Directed by: Darren Lynn Bousman
Starring: Tobin Bell, Betsy Russell, Costas Mandylor, Scott Gordon-Patterson, Scott Patterson
Visible crew/equipment: Several times in the movie you can see a stunt double for Donnie Wahlberg, like when he tries to hang himself. Art runs over and there is a wide shot focusing on both of them. No slo-mo required, but you can see it's a stunt double.
Jigsaw: "Cherish your life" is the motto this whole organization is built on. Cherish your life... your life.
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.