Director/Actor Jones gave each cast member a copy of Albert Camus' "The Stranger" to read so that they would understand alienation, a big theme in both the novel and the film.
After the hotel scene, when Pete and Melquiades Estrada drop the girls off at their vehicle, Melquiades Estrada gets back in the truck and puts the window up, a crew member can be seen in the reflection of the window.
Mike Norton shows no sign of beard growth during the entire stretch of his captivity. He should have had at least several days of beard growth by the time he and Pete made it to "Jimenez".