Director Kevin Greutert mentioned in the commentary track that the twitching and shivering Amanda (Shawnee Smith) does in her scenes with Cecil (Billy Otis) was real due to low temperatures and rain in Toronto at the time of filming. Shawnee couldn't stop shivering because she was cold and they were shooting outdoors.
A week before filming began, director Kevin Greutert was informed that the film would be post-converted to 3D. He was upset at this decision as he hadn't planned or storyboarded such a move. The idea was dropped for this installment due to time constraints but resurrected for the next film in the film series, Saw 3D - Vollendung (2010).
VH1's reality show Scream Queens (2008) winner Tanedra Howard won a role for this film. She plays Simone.
While it is used as a plot point for the film, an insurance company cannot void coverage for seeking an alternative "non-traditional" therapy. They don't have to pay for it, but it cannot be grounds to void coverage.
Is the first installment of the franchise where Billy the Puppet appears in person to deliver the rules of a game, rather than a warning or a congratulations message.