In the Mouth of Madness

In the film, the works of Sutter Cane are occasionally quoted. Most if not all of these quotes are actually taken directly from several H.P. Lovecraft short stories with some adaptations to fit them into the film story. Most notably, in the scene where Styles reads to Trent as he gazes into the abyss--her speech lifts much of its description, including such elements as "the illimitable gulf of the unknown" from the last few paragraphs of Lovecraft's "The Rats in the Walls." In an earlier scene as well, Trent reads a line verbatim from Lovecraft's "The Haunter of the Dark," in reference to the black church being "the seat of an evil older than mankind and wider than the known universe."

Trent and Styles drive for at least 18 hours through landscapes of cornfields in vast flatness, to reach the center of New Hampshire. New England isn't that big, and New Hampshire isn't that flat.

The closing credits exclude all the main characters and begin with Frances Bay

The original theatrical release had the 1987-1994 New Line Cinema logo at the opening. The 2013 Blu-ray from Warner Bros. plasters it with the modern New Line logo. But the 2018 Blu-ray release from Shout! Factory restores the original logo.