The Snake Scene

The boys drive to Wyoming to a mountain peak 8,734 feet in elevation to look for a cave full of hibernating bears. They secretly follow a woman to the cave and go inside. There is a lot of snow on the ground outside, so it must be freezing, but a short distance inside the very large cave, they see lots of snakes lying on the floor. Marty announces that they're Timber rattlers, drawn in by the heat. (True Timber Rattlesnakes are not found in Wyoming, but the name is a common one for any rattlesnake found in the woods, so I'll excuse them for that. And snakes do overwinter together in dens, so that's not entirely unbelievable, even though they wouldn't be found in a pile on the floor of a giant cave.) The snakes are blocking the way to the bear cave and the boys are afraid to walk through them, so Marty devises a plan to get snow from outside the cave and cover the snakes with it. (That might actually work. Some snake photographers will put a nervous snake in a cooler full of ice to slow it down so it can be posed. That's where the phrase "chill out" comes from. Maybe. I just made that up.)

As the boys walk over the snakes and the snow we see several rattles sticking up out of the snow shaking, as we hear rattling sounds. One of the snakes pops up out of the snow between the youngest boy Marshall's legs and he screams, then he jumps straight up after the snake strikes up at him. Marty chastizes him for screaming, which could wake the bears and kill them all. 

Sure enough, once they get past the snakes, they find a group of bears sleeping in a large open area in the cave, and they wake them up. The bears attack the boys, and as they run towards the exit they see the snakes again and stop, because all the snow has melted. In fear for their lives, figuring their chances are better with the snakes than with the bears chasing them, they run through the rattlesnakes as we hear all sorts of rattling sounds and the snapping sounds of the snakes striking at them. They don't get bitten, and even more surprising, the bears don't keep coming after them.

The snakes we see in the movie are a mixture of real live rattlesnakes and obviously fake plastic snakes. One of the fake snakes strikes up when someone pulls on a line connected to it. The large rattlesnake we see is a Western Diamond-backed Rattlesnake, which is not found in Wyoming, and I think there are another couple of juvenile diamondbacks in the shots we see. The tails sticking up out of the snow, and the snake that strikes at Marshall are all mechanical contraptions.