Why was the spider-walk scene cut? Friedkin thought it came too early in the film, and that makes a certain amount of sense — the scene takes place before Father Karras gets involved with the case, and Karras’ entry really signifies the supernatural elements of the film coming together and rearing their ugly head in full force. Up until then, there’s an air of doubt over everything — the sense that there has to be some sort of rational explanation for everything going on. The spider walk changes that — it’s a creepy, strange, nightmare-inducing moment that points to something horrifying and preternatural.
During the scene in question, Chris returns home to find the house empty and Regan seemingly asleep — with her bedroom window open. Chris’ assistant Sharon was supposed to be watching Regan, but she had to run out for something — leaving the sick child in the care of Burke Dennings, the alcoholic director of Chris’ film. But Burke is nowhere to be found. Chris assumes he simply, and irresponsibly, left Regan alone. Not so — a man shows up at the house to inform Chris that Burke is dead. And that’s when it happens — suddenly, Regan is on the stairs, upside down, and crawling towards everyone like a spider. She stops at the bottom of the steps, opens her mouth, and spits blood with a horrifying sound.
Originally, the scene was shot with Regan sporting a fake lizard-like tongue licking in and out, but the bloody mouth version is far scarier. Perhaps most impressive of all is that stuntwoman Ann Miles performed the scene with no harness; she really came down those stairs upside down.