The other great hurdle facing Cronenberg, his cast and crew on Scanners were the ambitious makeup effects. While much of the film is devoted to action, chases, and gunplay, Scanners is remembered for two classic sequences: a scene early in the film in which Revok causes the head of another scanner to explode during a demonstration of scanning, and a climactic telepathic battle between Vale and Revok that features swelling, bursting veins on both men’s arms and faces, eyes erupting from heads, and one of the two powerful scanners going up in flames.
The exploding head — the iconic image most associated with the film — was a plaster and gelatin duplicate of the head of actor Louis Del Grande that was filled with corn syrup (for blood), scraps of latex, wax, “a lot of stringy stuff,” and apparently even some leftover burgers. But according to a featurette on the Criterion Blu-ray, the initial plan to detonate the head with explosives wasn’t working. So special effects supervisor Gary Zeller, after telling everyone to get clear, lay down behind the head, pointed a shotgun filled with kosher salt at it and blew the thing up from the rear.
“It’s an incredible shot,” said the director in Cronenberg on Cronenberg. “Incredibly gruesome, but also quite beautiful.” The producers were so worried that the scene would land the film an X rating that they wanted to shoot a less gory version. “I said, ‘Sure, go ahead,’” remembered Cronenberg. “They shot three more heads blowing up in various ways, but I wasn’t there to watch them. I just went back to my Winnebago and took a nap. I wasn’t interested. I had the one I wanted.”
As Scanners comes to a close, Vale is captured by Revok and learns a bitter truth: the two of them are brothers, and Dr. Ruth — killed earlier in the film — is their father. Ruth gave their mother a prototype version of Ephemerol, meant as a tranquilizer for pregnant women, and discovered the unintended side effect that it turned humans into scanners — with his sons becoming the most powerful of them all.
After Vale refuses to help Revok with his plan to create a new race of scanners and subjugate humanity, the two engage in a vicious telepathic battle that literally tears them apart. As originally shot, the scene didn’t work, so Cronenberg reshot it — this time with the aid and expertise of legendary makeup artist Dick Smith, who had been serving as an off-set consultant for the film but came to Montreal to lend his genius to the final battle.