Sam Shepard was offered a role in the early 80’s for a film called The Right Stuff. The film was to be shot in the Mojave Desert of California. One of the reasons Shepard was interested in the film was a chase scene on galloping horses, a man (his character) chasing his wife through the cactus and stuff. Having his own horse, a roping horse named Roany which he had a good connection with he asked from the director if it would be okay to use his own horse. The director readily agreed. He is met by the stuntman and head wrangler upon arriving at the set for the first day of shooting. They are not keen on the idea.
Listen to Sam Shepard tell the story (WARNING: someone get’s hurt and it’s funny):