The animation of He-Man pulling the gate from its hinges and throwing it was first seen in Castle of Heroes (1983) and was reanimated for a sequence featuring BraveStarr in Thoren the Slavemaster (1987).
Backgrounds are reused from the dimension inside the white hole as seen in The Taking of Grayskull (1983).
The Star Wars: Episode IV - A New Hope (1977) inspired chess game also appears again in Colossor Awakes (1983) & Ordeal in the Darklands (1983).