Robert Mitchum visited his son Christopher Mitchum during filming. Director Howard Hawks asked the elder Mitchum to reprise his El Dorado (1966) role as a drunken sheriff, but Mitchum claimed he was now retired. John Wayne responded, "Mitch has been retiring ever since the first day I met him."
John Wayne was in poor health during filming, and frequently had great difficulty getting on and off of his horse. He was also still recovering from tearing a ligament in his shoulder while filming The Undefeated (1969).
During a break in filming, John Wayne collected his Best Actor Oscar for True Grit (1969) from Barbra Streisand at The 42nd Annual Academy Awards (1970). When he returned, every member of the cast was wearing an eye patch, including his horse.
Howard Hawks had originally planned to re-team John Wayne with Robert Mitchum, his co-star in Hawks' hugely popular previous movie, El Dorado (1966). Finding that production company Cinema Center Films would not pay for two such expensive stars, he went instead with Jorge Rivero; Rivero, a major star in Mexico but virtually unknown in the US, spoke little English and could not hold his own in scenes with Wayne. Hawks also regretted casting Jennifer O'Neill, finding her difficult to work with and more interested in her hair than her performance.