The movie was rushed into production. The original script was discarded and rewritten in one week, starting in March 1989. Principal photography had finished by the end of April, editing was done in May, and the movie was first screened at a film festival in July of 1989.
The original screenplay for the movie was written by producer Arthur Gorson and S.J. Smith, but Monte Hellman disliked this screenplay, and with Gorson's permission hired Rex Weiner to write a completely new screenplay. This was further revised by Hellman himself, his daughter Melissa Hellman, and Steven Gaydos. The final script is credited to Carlos Laszlo, who in reality was the newborn baby of Rex Weiner. Carlos and his parents also have a cameo in the film as the family who Laura sits down next to at the hospital. The original rejected script by Gorson and Smith would subsequently form the basis of what eventually became Natal Sangrento 4: A Iniciação (1990).
The movie that the gas station employee is watching on the TV is Sombras do Terror (1963), also directed by Monte Hellman, uncredited.
Director Monte Hellman attended a screening of the movie in July 2008 at the Alamo Drafthouse in Austin, Texas where he said he thought it was his best work, though not his best movie.
Dr. Newbury's assistant is played by Melissa Hellman, the daughter of director Monte Hellman. She also assisted her father with the final draft of the script.