Retroactive Recognition: Late into the line's lifespan, Mattel held a contest for fans to design their own character, which they would then make into an official action figure (the plan never came through). The winner was Nathan Bitner, who grew up to design characters for the Halo series.
Saved from Development Hell: The winning character design from the contest mentioned above was never made for unknown reasons, though Mattel came through with every other promised prize. Finally the character, Fearless Photog, was made as part of the Classics line for the 30th anniversary of the franchise.
There were plans for a prequel to both MotU and She-Ra featuring an ancestor of the main characters, He-Ro. Yeah, those never saw the light of day, but He-Ro has recently been released as part of the MotU Classics toyline.
Similarly, Vikor, He-Man of the North, is a MOTU classics figure based on the earliest stage of what would become He-Man's design.
The Monogram figure kit line was almost cancelled in favor of another project (which didn't itself see the light of day): a 1/25 scale Dodge Diplomat police car.
There was to be a sequel series called He-Ro Son of He-Man, featuring He-Man's adopted son, but nothing came of it.
Awesome, Dear Boy: Frank Langella loved being in this movie, and will talk about it whenever given the chance.
Contest Winner Cameo: In the DVD Commentary, Gary Goddard mentions how Mattel held a contest where the winner would get a role in the film, but they didn't tell them about this until very late in production, so the winner just got a cameo as one of Skeletor's guards near the end with his face hidden under a pig mask.
Doing It for the Art: The final sword fight between He-Man and Skeletor was filmed at the very end, after the money ran out. The director paid out of his own pocket to get that vital sequence filmed and have a finished movie, which is why the set and lighting change so dramatically just for the lions share of the duel.
Role Reprisal: The Mexican Spanish dub use the same voice cast from the animated TV series.
What Could Have Been: There were plans for a sequel, which got as far as early production. However, due to monetary issues Cannon Films lost the rights to the franchise, and the whole project, along with the cancelled Cannon Film's Spider-Man production assets, eventually turned into Albert Pyun's Cyborg