Vincent D'Onofrio purposefully mouth breathed during the entire production to create a unique timber and respective speech patterns. He then added a "nose squeak" after finding that some persons who lost their nose secondary to trauma or cancer produce a high pitch sound after completing certain sounds.
Vincent D'Onofrio purposefully developed a bad and uneven suntan, gained a significant amount of weight, bleached his hair, and wore improperly fitting skateboard apparel. When he reported to the set, he arrived in character.
Warner Brothers was not comfortable with the significant drug content and the John F. Kennedy assassination sequence, and initially wanted an edited version of the film for a wide theatrical release. The scenes remained, but the film then was only given a limited theatrical release.
Writer Tony Gayton said that the script to this movie was not written to be produced but to be a writing sample, something wild and experimental he could show producers to get work. He was very surprised when Castle Rock wanted to produce it.
Before Morgan pulls the trigger on the empty revolver, Danny has a fuzzy flashback in which he can't remember if the gun dealer said whether it was an 8 or 9 shot revolver. Smith & Wesson does not, nor have they ever made, a 9 shot .357 magnum revolver.
Chandra West and Deborah Kara Unger were both in The Salton Sea (2002) and White Noise (2005). In both films West plays the spouse of the protagonist, and in both films she dies. The protagonist then goes on a search to find out what happened to her, where he meets the character played by Unger, and befriends her.