Some of these pictures and descriptions may give away plot details that you might not want to know before watching the film.
This is that psychedelic movie where a Harvard brainiac eats some Mexican magic mushrooms and gets inside an isolation tank and then freaks out so bad he turns into an ape man and eats a raw sheep. But before that, he goes into a Mexican cave with some Hinchi Indians (whose hobby seems to be balancing the biggest rocks ever) and he takes the drug for the first time. It makes him hallucinate a lot of crazy things, including some lizards and a big Burmese Python wrapped around his neck. The snake we see is a real live Burmese Python, and it really seems to be around William Hurt's neck, and, if you've ever done this with your pet Burmese, you know it can feel pretty panicky if the snake starts to tighten up, so kudos for Hurt for not dying so he could go on to get his oscar for kissing that guy in prison.