Novice director Ed Sherin, who had guided "The Great White Hope" to stage success, was Lancaster's surprise choice to direct "Valdez Is Coming." Ironically the film version of "The Great White Hope" directed by Martin Ritt was filmed in Spain at the same time "Valdez" was filming.
At the end of the film, when Valdez is riding hidden between two horses, a wire is visible holding the horses' bridles together, so that they won't separate during Lancaster's close-up.