When Henry is riding on horseback to catch the stagecoach carrying Julia, the horse loses its footing and plows into a ditch throwing Henry several feet in the air. The scene was not planned and that was actually director Jack Nicholson flying head first into the ditch. Fortunately, neither the horse nor Nicholson was injured save for some bruises. Later, upon viewing the footage in dailies, Nicholson exclaimed, "That's A Keeper!"
Jack Nicholson original want to direct and star in Moon Trap. The only studio offer the deal was United Artist, which volunteered $2-3 million (only if Nicholson would star in the film). But Nicholson didn't want to star in the film. He insisted the film was logistically too ambitious for him to divide his attention between acting and directing. His acting fee was over $1 million per picture. He volunteered to play Webb the grizzle old goat-to cover himself in gray hair and matted beard. But over the time George C. Scott,Lee Marvin,Marlon Brando, Jon Voight and Dennis Hopper were approached to play Webb. The movie was screenplay by Alan Sharpe. So Nicholson dropped the project and turned his attention to Goin' South.