While serving as executive producer, author Whitley Strieber, whose 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."
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.
Director Philippe Mora wanted star Christopher Walken involved in the casting of whomever played 'Anne Strieber'. It was Walken who suggested Lindsay Crouse.
The scene in which Whitley Strieber (Christopher Walken) holds up the Alien's face mask over his face was improvised by Walken and was 2 minutes long with Walken trying on multiple masks, but the footage only appears in the film for a few seconds.
Anne Strieber is referring to Joseph Campbell's four-volume compendium of World Mythology with her "Masks of God" observation.