Ward Bond (Major Seth Adams) and Robert Horton (Flint McCullough) did not get along on the set. According to Horton, Bond spread rumors about his sexuality. The two men settled their differences two days before Bond died.
Although it was not publicly disclosed at the time, Ward Bond was already in terrible health when the series began. He was ill with high blood pressure, and had been ordered to reduce his workload. However, he continued to drink heavily while working on the series.
Gene Roddenberry described his original concept of Star Trek (1966) as "Wagon Train to the Stars." Gene L. Coon (the writer/producer who invented the Klingons and developed many other elements of the Star Trek universe) wrote 23 episodes of Wagon Train.
Ward Bond's final acting project. Bond died of a heart attack during the fourth season. No explanation was ever given on the show for Major Seth Adams' disappearance.
Martin Landau said he was appearing on this series when Ward Bond learned that he was a Jewish actor from New York. Instead of throwing a fake punch during a fight scene, Bond reared back and deliberately cold-cocked Landau when they were filming the show.