Director David Cronenberg fired a .357 Magnum loaded with blanks just off camera to make Smith's flinches seem more involuntary; this was Christopher Walken's own idea.
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.
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.
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.