20 Things You Didn't Know About The Thing
14. A Double Amputee Was Used For The Defibrillator Scene
Surely the most memorable scene in the entire film is the traumatic defibrillation sequence, where poor Dr. Copper (Richard Dysart) attempts to revive Norris (Charles Hallahan), only for Norris' chest cavity to open up, turn into teeth, and bite Copper's arms clean off.
The horrifying scene was achieved by having a double amputee serve as a stand-in for actor Richard Dysart, while wearing false arms which could be torn away by the practical effect.
But Carpenter also wanted to take things further, and so had the double wear a mask of Dysart's face for the wide shot.
It's obvious if you're looking for it, but most viewers are so distracted by the severed limbs that the last place they're looking is Copper's face.