Season 2's "Mind Stealers From Outer Space" and Season 3's "The Boy Who Knew Her Secret" have almost exactly the same plot. (Imposter aliens from outer space try to take over the planet through mind control.)
First Wonder Woman episode to not feature Wonder Woman/Diana Prince smiling at the end of the episode
The director of this episode, Michael Caffey, is the father of Charlotte Caffey of the musical group, The Go-Go's.
There was a special two part story arc involving Andros, a character from Outer Space who was part of an "Intergalactic Space Council" in the first season, called "Judgement from Outer Space." There was a similar two part story involving Andros the 2nd, the first Andros' son, in season 2, in "Mind Stealers From Outer Space, Part 1 and 2".