Originally intended by the writers to be 2 movies, Saw: The Final Chapter: Parts 1 & 2 with Cary Elwes' return being the big finale of Part 1 and then Chapter 2 would tie everything up. After Saw VI (2009) didn't do well at the box office LionsGate decided that the 2 parts would be turned into a single film. It has been hinted at by the producers and writers that lost elements from the original 2 part script will be used in future sequels or prequels whenever LionsGate decides to revive the franchise.
It has been revealed by LionsGate and the producers and writers that although this is the end of the Saw franchise for now more movies are planned for the future, although it may be several years before a new one comes out.
Although never mentioned in the film, there is a two month time lapse from Jill's testimony in the Internal Affairs department until the Bobby Dagen game which is the main plot of the film. This time period was enough for Hoffman's injuries to heal and of course for the preparation of the Bobby Dagen game. The opening sequence with the "love triangle" trap is supposed to be long before the film's main events.
(at around 18 mins) The garage trap was written for an earlier film in the series, but the producers felt it was "too disturbing" to show in a film. For an unknown reason they finally allowed it to be filmed.
The infamous bathroom trap has appeared in every film except Saw IV (2007). It appears in Saw (2004), Saw II (2005), Saw III (2006) and Saw 3D. The large iron door that leads to the bathroom can be seen in Saw V (2008) and appears in Saw VI (2009) through archive footage.
The only film series in history to have its first seven films released in consecutive years from 2004 to 2010. That record was originally held by the Police Academy series, whose first six films were released consecutively from 1984 to 1989.
On January 25, 2010, news hit that director David Hackl had officially been let go from the film. His replacement was to be series veteran Kevin Greutert, who directed Saw VI (2009) and served as editor for Saw (2004), Saw II (2005), Saw III (2006), Saw IV (2007), and Saw V (2008). This move was due to the fact that Greutert had signed to direct Saw VII's main competition, Paranormal Activity 2 (2010), which was to be released on the same day. Fearing low box office grosses, Lionsgate enforced Greutert's contractual obligation to the franchise.
At the 2010 San Diego Comic Con the film was referred to as "Saw 3D The Traps Come Alive" at a press conference, and many tabloid's reported this was the movies official title. The next day the producers confirmed the movie's title was simply "Saw 3D" and "The traps come alive" was only a tagline.
(at around 1h 21 mins) Near the end of the film, right after Hoffman destroys his hideout, there is a crate in the background with "CWD 5" on it. This is a prop from the 5th season of Canada's Worst Driver (2005), filmed at CFB Borden, Ontario.
Gina Holden who plays Bobby Daegen's (Sean Patrick Flanery) wife Joyce, appeared in Final Destination 3 as Carrie Dreyer, a girlfriend killed in the opening premonition. Chad Donella, who portrays Detective Gibson, was in the original Final Destination as Tod Waggner, Alex Browning's (Devon Sawa) friend that was the first survivor killed.
Among those attending Bobby Dagen's victim support meeting, are Mallick (the junkie from Saw V), Simone (the predatory lender from Saw VI), and Addy (the diabetic from Saw VI) can be seen in Bobby's victim support meeting.
The idea that Dr. Gordon throws the hacksaw out of the bathroom, away from Hoffman's reach, according to the film's producers, Oren Koule and Mark Burg, was Cary Elwes' own. The film's writers, Patrick Melton and Marcus Dunstan, claim that the hacksaw simultaneously being thrown into the camera as a 3D effect was the idea of the film's director, Kevin Greutert.
The original intention with the opening scene in the shop window was that it would end with the reveal that Jigsaw was watching the action unfold in the crowd (the timeline would mean that he was still alive at this point). Standing beside him would have been his accomplice - Dr Gordon.
at around 17 mins) In Jill's dream sequence, Hoffman says to her "You wanna know the only thing wrong with killing you, Jill? I can only do it once." Including the dream sequence, we see Jill killed twice in the film (go-kart trap and reverse bear trap).