Director David Cronenberg had to re-shoot the scene in which John Smith has his first premonition. It showed a little girl's room burning and a small E.T. doll could be seen on one of the shelves. The scene had to be re-shot when Universal Pictures threatened to file a lawsuit against them.
The "sweat" on Christopher Walken's face during the "burning bedroom" sequence was in fact a flame-retardant chemical that had been sprayed onto him. The resulting effect, which hadn't been anticipated, looked surprisingly dramatic on film.
This film (and Stephen King's novel) are both loosely based upon the life of famous psychic Peter Hurkos. Hurkos claimed to have acquired his alleged powers after falling off a ladder and hitting his head.
The gazebo where the murder took place was built for the film, and was later donated to the town of Niagara-on-the-Lake, Ontario, where it was filmed and is now a favourite spot for wedding photographs.
During the time Michael Kamen was composing the music for the film in London, he would play the score on the piano in his home. He received several complaints by his neighbors who asked, "Can you please stop playing that music? I can't sleep and it's giving my family nightmares."
Written in 1979, the novel by Stephen King was the first book of his to reach #1 on the bestseller list (hard cover), a milestone for King who said it was "one of my most successful ever." It was 428 pages.
David Cronenberg wanted to change the name of Christopher Walken's character: "I'd never name someone 'Johnny Smith'", he quipped, but in the end it was left as is. The book does specifically mention how it sounds like a fake name.
There are several deleted scenes that were filmed and completed but have never been seen publicly and are thought to have been discarded prior to the film's release. Among them: - A prologue showing John Smith as a boy (played by Stephen Flynn) who sustains a head injury during an ice hockey match. The scene features actor Sean Sullivan as John's father. - An alternate scene of John Smith's vision of the Camp David scene (featuring Martin Sheen) in which John himself appears in the vision as a helpless spectator. Photos of these scenes appeared in the December 1983 issue of Cinefantastique.
One of only three David Cronenberg films that do not have a score by his friend, composer Howard Shore. This was due to studio politics in which Paramount wanted a more familiar composer to write the music for the film. Michael Kamen, who had written the music for the film Venom (1981) for the studio, was chosen instead.
The film makes reference to 'Sleepy Hollow' which, like this film, is about a schoolteacher. In the novel, Johnny Smith compares his coma and subsequent recovery to 'Rip Van Winkle,' another short story written by Washington Irving. Christopher Walken went on to play the Horseman in the Tim Burton Adaptation.
Martin Sheen's character says he has had a vision that he will become the President of the United States. Sheen went on to play the President of the United States in the mini series Kennedy (1983) and in The West Wing (1999).
In the final scene when Sarah is crying and hugging Johnny, we hear her stop crying for a few seconds to tell Johnny that she loves him, but since her mouth is obscured we don't actually see her say it. The original script did not have her saying this. Her voice was dubbed in later in order to have some closure for Johnny.
In the "nuclear war" scene, Greg Stillson, Martin Sheen's character, threatens to "hack off" someone's hand and put it on the scanning screen. An earlier version of the script actually had Stillson shooting the man and putting his dead hand on the screen.