An instantly identifiable character actor best known for playing cops and coaches, Hallahan seemed too sturdy and flat-out real to succumb to the body-shifting alien. This was the perfect setup for Bottin, whose labor-intensive fx were obsessively detailed. As Hallahan noted in the film’s making-of documentary, “You’d walk into their model room to see what they were going to eventually come up with … and it was incredible to see.” Hallahan spent ten days with Bottin’s crew, and they studied his body and physiognomy like they were planning to clone him. “They molded my face in a lot of different expressions, then my hands, my legs, torso,” he said, adding that “they even took photographs of my chest without a shirt on, and they assigned one person to make the hair pattern match.”

Hallahan’s castmate and friend, Richard Dysart, occupied the unenviable role of the doctor who plunges his paddles into the character’s chest, which opens up as a jagged set of jaws that bite the poor guy’s hands off. When Dysart walked onto set and saw what he believed to be Hallahan in the bare-chested altogether, he was revolted. “[H]e said, ‘Put some clothes on that guy for God’s sake, disgusting!’ And he came running over, and it wasn’t until he was right on top of me that he realized that was fake.” 

Dysart couldn’t have paid Bottin’s crew a higher compliment. “When I see the picture,” said Hallahan, “I know what my chest hair pattern looks like from looking at myself mirrored for 50 years. I’m shocked how accurate it is.”