The test footage, produced by 1936, received negative reactions from film exhibitors across the U.S., especially in small towns; many gave their opinion that the concept of an Earthman on Mars was just too outlandish an idea for midwestern American audiences to accept. The series was not given the go-ahead, and Clampett was instead encouraged to produce an animated Tarzan series, an offer that he later declined. Clampett recognized the irony in MGM's decision, as the Flash Gordon movie serial, released in the same year by Universal Studios, was highly successful. He speculated that MGM believed that serials were played only to children during Saturday matinees, whereas the John Carter tales were intended to be seen by adults during the evening. The footage that Clampett produced was believed lost for many years, until Burroughs' grandson, Danton Burroughs, in the early 1970s found some of the film tests in the Edgar Rice Burroughs Inc. archives. Had A Princess of Mars been released, it might have preceded Walt Disney's Snow White and the Seven Dwarfs to become the first American feature-length animated film.
