Other mistake: After the exploding head incident, Revok is captured at gunpoint. Minutes later, the man pointing the gun at Revok racks the slides; no cartridge is ejected, which means the entire time prior to this moment the handgun was useless, as there was no round in the chamber. Cocking the hammer, taking the gun from double-action to single action, would have achieved the Hollywood dramatic effect without a common sense error on gun functionality.
Scanners (1981)
1 other mistake - chronological order
Directed by: David Cronenberg
Starring: Patrick McGoohan, Jennifer O'Neill, Lawrence Dane, Stephen Lack
Continuity mistake: After the scanner's head explodes, not only is the table clean in the next shot (as already submitted) but Revok himself is as clean as a whistle. He was sat right next to him. (00:12:33)
Paul Ruth: How do you feel?
Cameron: I feel... crystal clear.
Trivia: Scanners is identified as having the first known media depiction of psychic activity directly or indirectly causing nosebleed. This concept has since become widespread in movies, television, and comic books/graphic novels.