The closing credits run for 11 minutes. This is because without the extra time, the movie would have been considered too short to release theatrically.
The sound of Matilda Dixon's wailing throughout the film is really the sound of an elderly woman's groaning in bed. The sound was both sped up in the parts where Matilda screams, and slowed down in the places where she gurgles and breathes heavily.
(at around 45 mins) The "Sensory Deprevation Tank" is actually an MRI machine.
The theatrical poster has an MPAA R rating posted at the bottom, however the film is rated PG-13 by the MPAA.
In a different version of the film's script, the creature only appears in the final act. The studio was not satisfied by this, so they brought Stan Winston in to create a new Tooth Fairy that would be seen throughout the film. The original design (by Steve Wang) bears no resemblance to the new version, although it is the basis for the McFarlane Toys figure released in 2002.