Before filming began, John Wayne had to lose most of the weight he had put on in order to play Rooster Cogburn in True Grit (1969).
John Wayne became good friends during the shoot with Rock Hudson and even joked that he'd rather have been born with Hudson's movie star face than his own.
During filming, John Wayne fell from his horse and fractured three ribs. He couldn't work for almost two weeks. Then he tore a ligament in his shoulder and couldn't use one arm at all. Director Andrew V. McLaglen could only film him from an angle for the rest of the picture. Wayne's only concern, throughout, was not to disappoint his fans, despite being in terrible pain.
Rock Hudson admitted in a 1980 interview that he thought the movie was "crap", and attributed its box-office success only to the fact that it immediately followed True Grit (1969). However, he had fond memories of the filming because he became a close friend of John Wayne and Roman Gabriel.