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."
Director Philippe Mora had originally met author Strieber in London in the late 1960's. After Mora made his film Death of a Soldier (1986) in the 1980's, he ran into Strieber again. They got to talking and Strieber mentioned his recent experiences. Mora told Strieber that if he got around to writing about them, to let him know.
The filmmakers had one week in NYC for filming exteriors. During this time, director Philippe Mora was assigned an assistant director who turned out to be elderly and deaf. The deafness led to some difficulties, but things managed to work out for that week.
Whitley Strieber's Alien Contact books are usually cataloged as "Psychical Research" or "Paranormal". However, the cassette audio-book of Communion, read by 'Roddy McDowell' and produced by a Hertfordshire company called "Redback", simply has the word "FICTION" on the back of the inlay. This could have been a compromise to preserve the credibility of a start-up company and increase publicity for Strieber at the same time.