When He-Man enters Castle Grayskull and stands in front of the Window of Spirits, he utters a line which is almost completely drowned out by the background music. If one listens closely, the words "Maybe we can reach her in the Window of Spirits" can still be made out.
This was the first created episode of He-Man, but it was aired as the fourth. The writers actually had worked out an origin story for He-Man, but it was never animated, apparently for reasons of length. Much of it was later worked into the origin story for She-Ra.
This is one of the three stories edited into the direct-to-video movie 'The Greatest Adventures of All' which had a special premiere at Mann's Chinese Theatre in Los Angeles. The other two adventures being Teela's Quest (1983) & Colossor Awakes (1983).
He-Man's reaction to the rock creature and his subsequent fighting stance were used again in Evil-Lyn's Plot (1983).