The outfit that Harry Dean Stanton wears was modeled from a tintype photograph of one of his actual relatives, taken during the time period in which the story is placed.
Maria Potts ("Xochitl"), during one of her many nude horse riding scenes, fell off of her horse. Though not severely hurt, during a scene filmed soon after where she wrestles with Cliff Potts, many of her reactions of pain are real, the result of her injuries.
Cliff Potts and Maria Potts were husband and wife at the time of filming.