This is the only time that a missile is fired from the J2.
A prop from this episode was used in a key scene of Planet of the Apes (1968), creating one of the most memorable moments in science fiction film history. It is a replica of the torch of the Statue of Liberty, which was used in the ending of that film. It can be seen in the junkyard in this episode, around 8 minutes in.
Marcel Hillaire (The Junkman) was in both the first and last episodes of the third and final season.
Last show of the series.
Bob May later cited this as his favorite episode as The Robot.