Some of these pictures and descriptions may give away plot details that you might not want to know before watching the film.
"What a horrible way to die!"
"They're waiting to slither you!"
Boy is this a bad film - lousy plot, terrible action, bad acting and unbelievable dialogue. It's hard to find much worse. The only thing good I can say about it is that most of the natural history information about rattlesnakes it gives is accurate, even if the behavior of the snakes was not - we see snakes chasing people, biting people multiple times, and even biting the tires of moving vehicles!
The plot revolves around a den of rattlesnakes that becomes contaminated by CT-3, an experimental nerve gas developed by the military to cause behavior so violent that enemy soldiers exposed to the gas would kill each other. (That explains the tire biting.) The nerve gas is being horded by a rogue Army colonel. Of course, that doesn't explain why the snakes are spreading in a straight line for many miles and attacking any people they encounter. It seems like they would spread out.
There's lots of snake mayhem here: two young boys are viciously killed by rattlesnakes when they fall into a pit full of snakes; and snakes take over a house, coming through the pipes into a bathtub where a woman is taking a bath (that scene made for a cool poster, at least), killing everyone in the house, and causing it to burn to the ground.
The snakes used in scenes with people are not rattlesnakes, but plenty of rattlesnakes are used in other scenes, including repeated views of the same shot of a captive rattlesnake with only a couple of buttons on its tail (couldn't they at least have found a better looking rattle?) Many of the rattlesnakes are Western Diamond-backed Rattlesnakes dumped in piles as if that is their normal behavior. The snakes in the scene where the kitchen is full of snakes appear to be Western Rattlesnakes. The harmless snakes used are gopher snakes and other species I can't identify.
According to the credits, snakes and advice were provided by Hermosa Reptiles and Ray Folsum.