Some of these pictures and descriptions may give away plot details that you might not want to know before watching the film.
Mcteague, a fugitive on the run in the middle of scorching-hot Death Valley is crossing some sand dunes with his mule when he sees a large rattlesnake that strikes out towards him. Then he sees a gila monster crawling next to a chuckwalla. He says "Good lord, what a country."
The rattlesnake is a live Western Diamond-backed Rattlesnake, and the lizards are both live, too.