When Henry (Jack Nicholson) is riding on horseback to catch the stagecoach carrying Julia (Mary Steenburgen), the horse loses its footing and plows into a ditch throwing Henry several feet in the air. The scene was not planned that way, and that was director Jack Nicholson flying head first into the ditch. Fortunately, neither the horse nor Nicholson was injured, except for some bruises. Later, upon viewing the footage in dailies, Nicholson exclaimed, "That's a keeper!"
Jack Nicholson once said jokingly of this movie: "The director of this film is one selfish, demanding egomaniac, and the leading man isn't much better. All he wants to do is lie down in front of an air conditioner the whole day!"
During a 2016 Back to the Future convention, Christopher Lloyd was asked what's his favorite movie out of the movies he had done. He named this movie as the movie he had the most fun making, and wished that more people knew about it, calling it "one fun little movie".
Jack Nicholson personally selected movie newcomer Mary Steenburgen for Goin' South (1978) according to allmovie.com. According to the Turner Classic Movies website, Steenburgen "was sitting in the casting office waiting room, when Nicholson first encountered her. He noticed she didn't have a reading script, gave her one with three scenes marked off and arranged to read with her the following day." That reading session ended up going for around two hours.
According to the biography "Jack's Life: A Biography of Jack Nicholson" (1996) by Patrick McGilligan, there was regular on-set conflict between John Belushi and Nicholson, and the film's producers. Belushi allegedly made several demands on the production. The book states: "Belushi was one jarring note in the proceedings. On the one hand, Jack wanted to like the comedian, whose popularity was soaring. Belushi blustered and posed, but he was fundamentally sweet, the kind of guy Nicholson liked to take under his wing. However, Belushi had a short fuse. He made petty demands and fought with the producers, especially Harold Schneider, whose job it was to not lose fights. Belushi became progressively more sulky as filming dragged on, and partly in response to his behavior, his role seemed to shrink."