David Cronenberg once called this the most frustrating film he'd ever made. The film was rushed through production - filming had to begin without a finished script and end within roughly two months so the financing would qualify as a tax write-off, forcing Cronenberg to write and shoot at the same time. Cronenberg also cited difficulty with and antagonism between the leads, particularly Patrick McGoohan and Jennifer O'Neill.
In an interview with Film Comment, Stephen Lack recalled feeling under-the-gun during one of his first scenes on set. "There we were, the first day of Scanners and they had me get into this 18-wheel truck with four gearshift levers and have me drive into the shot. It was horrifying. I never drove such a thing and I was pretty disoriented," he explained. "We were set up on a feeder road to the highway, and all the camera crew and staff were there, and some car on the highway slowed down to gawk-and a truck on the highway rammed them from behind. There was a death and sirens, and the whole crew jumped over the storm fence to help out. I was given a slight reprieve of an hour to figure out the gears."
William S. Burroughs' 1959 novel 'Naked Lunch' contains a chapter concerning "Senders", a hostile organization of telepaths bent on world domination, a clear literary inspiration for this film. Cronenberg would later direct a film version of Naked Lunch (1991).
A very early treatment from 1976, entitled "Telepathy 2000" takes place in the future, begins with the protagonist (who is named Harley Quinn) telepathically raping a woman in a subway, and was set as a spy movie. In this version, a company called Cytodyne Amalgamate was breeding evil Scanners to take over the world and the U.S. Government was employing good Scanners to stop them.
Stephen Lack - billed as Steven Lack - who plays Cameron Vale, is now a successful and prolific painter.