A running gag on the show was the animosity/competition between Joe and the dog. Ironically, whenever they shot publicity stills, Higgins would almost always sit in the lap of Edgar Buchanan because he behaved better for him than other members of the cast.
Even though the Cannonball is supposed to be a wood burning locomotive, and the tender car is loaded with chopped wood, the smokestack is blowing pitch black smoke. It should be blowing mostly white or light gray smoke from the wood. The black smoke reveals the real-life locomotive actually burned oil. In episode 1, this is explained away by saying that they're burning ties from the railroad.
2003 DVD release of four first-season episodes by Brentwood Entertainment replaces the well-known opening theme with an uncredited, instrumental piece of music.