Second part of a planned trilogy, known as the "Strange Trilogy", by writer-director Michael Laughlin. The first part had been Strange Behavior (1981). A third was planned, but due to a lack of funding, it was never made.
The movie is a homage to the the golden age of science fiction films of the 1950s particularly Invasion of the Body Snatchers (1956) and I Married a Monster from Outer Space (1958).
The picture was cast with two 1950s era stalwarts in supporting roles. They were June Lockhart from the sci-fi TV series Lost in Space (1965) and Kenneth Tobey from The Thing from Another World (1951).
The character of Charles Bigelow was originally written with Michael Murphy in mind but his casting was rejected by EMI Films. In the end the role was cast with Paul Le Mat. Murphy had played the lead role in the earlier related film Strange Behavior (1981). In the Starlog 1983 article "Michael Laughlin: Attack of the Killer Cliches", Laughlin said "there didn't seem to be a good reason for his rejection. I guess it was a matter of personal taste".
A photograph of Steven Spielberg, famous at the time this film was released for E.T. the Extra-Terrestrial (1982) and Close Encounters of the Third Kind (1977), is seen in a file of photos of aliens at the Center for UFO Studies.
Bill Condon: The co-screenwriter appears in the 'National Informer's office, standing in the doorway listening in as Charles tells his story to Betty.