Storyboard artist Michael Swanigan was a Filmation fan, and often, in his storyboards, he would pay homage to previous Filmation shows. The season one episode "The Remedy" is famous for featuring Warlock from Blackstar, repainted as a Takdryl, and not so famous for featuring numerous physical stock movements from the Tarzan series repurposed for He-Man. However, in the storyboards for this episode we see that Michael Swanigan wanted another character from a past Filmation show to be reused. Here we see Balkar from Blackstar designed to play the role of Mitro. Sadly, this never came to pass and Mitro was specifically designed anew for the episode.
(click on the image to see it at full-size)