(at around 1h 10 mins) During the climax, in the storage area with all 101 dolls, you can see Jigsaw's doll from the "Saw" films sitting on the floor, and Edgar Bergen's doll Charlie McCarthy on one of the shelves. The doll that Detective Lipton throws over his shoulder in this scene is a replica of ventriloquist Jimmy Nelson's doll, Danny O'Day.
There are two different versions of the "Mary Shaw" poem. In the movie the poem goes, "Beware the stare of Mary Shaw. She had no children only dolls. And if you see her in your dreams, be sure you never, ever scream." On the trailer it was, "Beware the stare of Mary Shaw. She had no children, only dolls. And if you see her do not scream, she'll rip your tongue out at the seam."
"Billy" was not only the name of one of the dummies in this movie, but also the name of the puppet used by the Jigsaw killer in the "Saw" movies, also created by Leigh Whannell and James Wan.
The film was made into a haunted house at Universal's "Halloween Horror Nights" in 2007 in Florida.
Leigh Whannell was so unhappy with the finished product, due to studio interference, that he decided to write all future scripts on spec, as opposed to pitching an idea to a studio and then being paid to write the screenplay, as was the case with this film.
The film is dedicated to producer Gregg Hoffman. He died 2 years before the film had its theatrical release.