- The MPAA originally rated the film NC-17, due to the film's tone; director James Wan had to remove some content to secure an R rating.
- Detective Sing pursuing the Jigsaw killer was the last sequence to be filmed.
- The scene in which Gordon turns off the lights and whispers to Adam was written differently in the script. The characters were to cut open opposite ends of a long pipe with their hacksaws and speak through it. This sequence was actually shot, but later cut because director James Wan decided that the characters being able to cut through a pipe made no sense if they couldn't cut through their chains.
- Film's pre-production was only five days; it was shot and cut at the same time in 18 days (all of the bathroom scenes were shot in six days). The actors had absolutely no rehearsals. The rehearsal takes were actual footage for the film.
- Filmed in 18 days.
- Sundance showed the NC-17 uncut version. The actual theatrical R-rated version is cut and more finessed, and the sound and colors were evened.
- The car chase was filmed in the garage of the warehouse by turning off the lights, adding some fog, and shaking the cars while filming from the front.
- Principal photography was done in a converted warehouse. The bathroom set was built while the other locations were existing rooms redressed.
- Was the closing film for the Toronto Film Festival.
- Originally intended for a straight-to-video release. After positive screenings, it was given the nod to become a premier movie.
- Director James Wan took a gamble and took no "up front" salary for the movie and opted for a percentage instead.
- Contains many references to the films of Italian horror/giallo director Dario Argento. The creepy painted puppet is a reference to Argento's Profondo rosso (1975), while the unseen killer's black gloves are one of Argento's trademarks and can be seen in almost all of his films.
- Shots cut in the R-rated version, according to director James Wan and screen-writer/actor Leigh Whannell, included ones of Amanda sifting through the intestines, the fat guy struggle through the barb wire just to shorten the scene, and some forensic ones. The color was made more even and the sound was altered because the MPAA had problems with the tone of the original cut shown in Sundance.
- James Wan and Leigh Whannell wrote the script and submitted it to their manager. The manager then sent it to an agent in L.A. who summoned the two of them for a meeting. They were encouraged to shoot a scene from the script as a short film which they started passing around to studios.
- According to the DVD commentary, casting agent Amy Lippens asked director James Wan who he wanted to play the character of Amanda. On a whim, Wan suggested actress Shawnee Smith, on whom he had had a crush since his teen years. He was surprised when Lippens came back a few days later and told him that they had secured her for the role.
- The detectives track down a fire alarm to a warehouse in "Stygian Street". "Stygian" is the name of director James Wan's first film, which also stars "Saw" co-writer/actor Leigh Whannell.
- According to the DVD commentary director James Wan points out that many of the scare scenes in the film were nightmares he and Leigh Whannell had as kids.
- The sequel Saw II (2005) was approved for production the weekend this film opened.
- Every scene was filmed in a set of buildings that were rented out to movie crews. Many of the sets in the film were originally empty rooms with props put in by the crew.
- Jigsaw's puppet was completely made from scratch by the films creators (it was not bought at a store or a puppet that was altered).
- All of the bathroom scenes were shot in chronological order in order to make the actors feel more what the characters were going through.
- According to the offical SAW website, in a still image used in one of the flash scenes, Adam's last name is "Faulkner".
- After Amanda stabs her cell-mate she is searching with her hands through his guts, the guts are actually pig uterus.
- To help sell his concept for the film, Leigh Whannell shot a scene in which he appears to be ensnared in a bear trap. There were no special effects involved, he actually had to place the teeth of the rusty bear trap in his mouth to make it seem real.
- Leigh Whannell mentions in the DVD commentary that the scene where his character plunges his hand down a filthy toilet is a tribute to Danny Boyle's Trainspotting (1996).
- Cameo: [Oren Koules] one of the film's producers plays Shawnee Smith's dead cell mate.
- Casting director Amy Lippens chose her ex-husband in the role of Mark, the man who burns himself alive.
- James Wan and Leigh Whannell had tried to sell their script to studios in Melbourne before Hollywood bought and produced the movie.
- In the scene where Dr. Gordon begins sawing his foot off, Adam is heard screaming and crying in the background. His screaming and crying is the same one used from the very last scene during the final climax. The audio has been edited and relooped.
- The opening scene of Adam in the bath with the blue light floating over him was the very first shot of the first day of filming.
- 'Leigh Whannel' performed his own stunt underwater during the opening scene in the bathtub. He stayed underwater by having a crew member stand on his chest.
- James Wan wanted the camera movements to reflect the two main characters emotions and personality. He filmed Dr. Gordon with steady controlled shots and Adam as hand-held shots to capture their emotions of the situation.
- The two hacksaws used in the film by 'Leigh Whannel' and Cary Elwes were very break sensitive, so they had to saw lightly in the scenes when trying to cut their chains.
- All the black and white and forensic photos shown in the film were taken by the production still photographer. And were used as a last minute resort while editing the film.
- James Wan and the editor had trouble editing the film as they did not have enough shots they wanted and had difficulties editing some scenes including Dr. Gordon listening to his tape and The detectives in Dr. Gordon's office the first time they meet
- James Wan built the Jigsaw doll in the film.
- Shawnee Smith shot all her scenes in one day.
- The surveillance camera footage of Adam and Dr. Gordon was shot separately and spliced together during post production, which is the reason for the strange angle of the two characters in the footage.
- Monica Potter and Makenzie Vega shot their scenes in 3 days.
- Charlie Clouser had just 3 weeks to compose the score for the film.
- In the original draft, the Zepp character was to do strange acts with Alison's underwear in her draws, but 'Leigh Whannel' cut it out as he thought it was a bit 'too far' it was rewritten as the gun and the listening of the heartbeat
- The cloak Jigsaw wears in the film is actually turned inside out.
- The glow in the dark X painted on the wall in the scene when they lights turned out, was in fact a light projection of an X shape.
- 'Leigh Whannel' accidentally punched Michael Emerson in their fight scene in the final scene.
>>> WARNING: Here Be Spoilers <<<
Trivia items below here contain information that may give away important plot points. You may not want to read any further if you've not already seen this title.
- SPOILER: The only dummy used in the whole movie is the burned corpse of the man who is in the room, naked, with the safe and broken glass. All other corpses were played by the actors.
- SPOILER: The Jaw Splitter was also used in the original Saw short film, attached to a character named David. The scenario played out the same as the later version, with David escaping from the contraption seconds before it went off.
- SPOILER: Instead of the quadruple shotgun trap, the creators wanted a trap that consisted of two things that would spring from the walls and snap shut on Sing and fold him up into a box. They described it as an "iron cocoon." They decided against the idea, as it would have cost too much money for visual effects.
- SPOILER: According to an interview with Leigh Whannell, Adam and Lawrence were originally going to be trapped in an elevator.
- SPOILER: James Wan and Leigh Whannell returned for several re-shoots, but the original actors were unavailable by that time. Whannell played the parts himself, and Wan used close-up shots of the characters' bodies, avoiding showing their faces. Whannell plays Detective Sing (Ken Leung's character) entering the building with a shotgun, and the body of Sing falling down after being shot. Also, the close-up shots of Shawnee Smith's character's hands in her torture/murder scene were Whannell's, and he wore a wig to make his shadow on the wall appear more like Shawnee's.
- SPOILER: In contrast to the majority of popular horror films, all the victims who die are men.
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