While serving as executive producer, author Whitley Strieber, whose purported experiences serve as the basis of the film, expressed concerns about Christopher Walken's abilities in portraying him. When Strieber finally told Walken that he might be portraying him as a little too crazy, Walken replied "If the shoe fits."
Philippe Mora admitted in select commentary that he granted Christopher Walken more or less complete creative freedom for his portrayal of Whitley Strieber, allowing the actor to improvise his idiosyncratic quirks and lines of dialogue freely.
The scene in which Strieber laughs when he sees the visitors was Christopher Walken's natural reaction at seeing the alien designs and thinking they looked silly. Director Philippe Mora liked his reaction, thinking it made the scene more disturbing and kept it in.
Anne Strieber is referring to Joseph Campbell's four-volume compendium of World Mythology with her "Masks of God" observation.
Director Philippe Mora had originally met author Strieber in London in the late 1960s. After Mora made his film War Time Melbourne May 1942 (1986) in the 1980s, he ran into Strieber again. They got to talking and Strieber mentioned his recent experiences. Mora told Strieber to let him know if he got around to writing about them.