This episode was supposed to be a back-door pilot for a part-animation part-live action spin-off TV series about an invisible and animated Martian taking over people's actions, but it never took off.
This is one of very few episodes where Mister Ed is not a main character of importance to the plot.
This was the third episode to feature the Kirkwoods, but was held back until the end of the season to air as a special episode.