The Voice: Welcome home, Sidney. You're a survivor, aren't you, Sidney? What good is it to be a survivor when everyone close to you is dead? You can't save them. All you can do... Is watch.
In the final shot of the film, Jill's head moves slightly when she's supposed to be dead.
In the beginning, one of the girls mentions how bad the Saw series is. Erik Knudsen (who plays Robbie Mercer) was in Saw 2 as Matthew.