This slip-up comes at the end when Chris (Daivd Arquette) is looking through the "coccoons" for his Aunt Gladys. He finds her and removes some of the webs around her face. A minute later she's trying to light a cigarette and he tells her not to because the gas inside the mine will ignite. The giant spider comes and you can very plainly see webs over Gladys' shoulders draped almost like a shawl. They hop on the motorcycle and head out of the cave being chased by the spiders and the gas ignites when the generator is turned on. They come blazing through flames to the exit of the mine and Aunt Gladys no longer has the webs on her shoulders. I thought maybe the flames had burned them away, but I looked and saw her shirt had no charring to indicate being burned or any remnants of the webs whatsoever.