Continuity mistake: When the microwave explodes, the bucket of chicken disappears right after the explosion. (00:48:50)
Continuity mistake: When Julie moves through the alley towards whom she thinks is her mother, in the first shot from her she is seen from behind as she walks to the wall on her left, and puts her hand out to it, almost as if to steady herself. The angle changes to a front view, and she is now standing next to a stack of crates, with her hand down by her side. The next time she is shown from behind, she is once again standing by a blank wall, with her hand outstretched to it, before she runs to her "mother".
Other mistake: When He-Man is fighting against the centurions on the floating disks, he tells the others to get inside a building. As he opens the door to the building, not only does it fall right off the hinges, but his sword also falls right off his back, pulling his cape off with it just as the scene ends. (01:09:20)
Audio problem: The keyboard Kevin gets from the music shop seems to have an interesting trait, in that the high notes are on the left. This must either be bad "audio dubbing" or something to do with the shot perhaps being reversed, although I doubt this. It's most likely a post-production audio error as very very few keyboards or pianos are configured in this way.
Continuity mistake: The bald policeman who spends most of his time chasing Kevin, He-Man and the other Masters takes a shotgun from the music shop, cocks it, and then walks out. Upon sighting the Masters, he needlessly cocks it again, and then he cocks it for a third time before he actually shoots anything. He also has an apparently unlimited supply of ammunition for that gun - since it was not his in the first place, it is a cause for wonder where all his extra shells must come from.
Continuity mistake: In the scene where the mercenaries are introduced, in the first overhead shot, and in the close-up before their individual introduction, they are standing in line with Blade on the far left, followed by Saurod, Karg and Beast-Man. As Skeletor walks past them giving instructions, Karg and Blade change places.
Continuity mistake: In the first scene involving He-Man where he fights some of Skeletor's troopers and rescues Gwildor when two of them fire at him with RED lasers he deflects them back at the troopers but the lasers have turned BLUE. Duncan and Teela appear to help and their guns fire blue lasers but they never fire as He-Man has the situation under control.
Other mistake: When the robot troopers storm the music store, a keyboard (in a slow-mo scene) is blasted. But it does not end up being damaged or even scorched, even though it receives a direct hit.
Plot hole: When Gwildor tells Julie and Kevin that he can use the Cosmic Key to take them to any point in time they wish, Kevin asks just for them to go straight home. As Kevin and Julie go through the portal, Julie turns around and shouts to Gwildor to send them back before being dragged through the portal completely. When Julie wakes up in bed, she discovers that Gwildor has sent her back to the day her parents were killed. Julie never said where in time she wanted to go, so there's no way Gwildor could know to send her back to the day her parents died.