Some of these pictures and descriptions may give away plot details that you might not want to know before watching the film.
This movies is basically torture porn - one man torturing another man in the desert for 100 minutes, with a talking, fighting and murdering inbetween, and way too many whip pans, rack focus, and cameras circling and circling somebody. (Although that technique is fun when the tortured guy is handcuffed to a long chain with his arms around a saguaro cactus struggling to climb it to get free.) If you can stick it out, there is a reason for it all.
In the beginning we see a man leaving a cafe in the Mojave desert, wiggling his fingers in front of a glass terrarium with a rattlesnake in it. Next we see a mysterious guy come in the cafe and leave, with a wriggling bag on the seat of his truck. (Maybe he took the rattlesnake.) Then an hour later the first guy gets in the truck where the snake is loose under the seats. (Why is it loose? We don't know. Maybe we're supposed to think he let the snake out to guard his truck or something. He certainly wasn't driving around with it loose. He did have an ashtray with blooody cigarette butts and a cut off rattlesnake rattle, so maybe he was killing snakes for food or something. We never know.) The guy feels around under the seat and gets bitten by the rattlesnake. We only see him scream not the actual snakebite. From a distance we see him swinging a machete and hacking something in the truck, apparently the rattlesnake. Then he runs away clutching his hand and eventually falls to the ground where some drug dealers find him delirious. They beat him up, and he beats them up, and suddenly he's fine with no more symptoms from the bite. (Maybe getting beat up is the cure for snakebite?) He told them he sucked out the poison so maybe we're supposed to believe that worked even though they told him it was the worst thing he could do for a bite along with running. When the truck's owner gets back into the truck he throws out a couple of things that we are supposed to believe are pieces of the snake. The whole snake scene really doesn't make much sense, which is unusual because the rest of the movie does (except for saguaro cactus in the Mojave Desert....)
At least they didn't kill a rattlesnake just for the movie. I'll give them credit for that - or maybe I should credit the American Humane Society. The snake we see is a Western diamond-backed Rattlesnake.