Alternative Character Interpretation: Whether the Mouse King is a Jerkass Woobie. Hints are his return of Clara's slipper to Clara the next night, hinting some hint of (somewhat perhaps grudging) kindness, which shows a small displaying hint of a Jerk with a Heart of Gold. While he does threaten Clara's kitten later on, it is slightly justified when Clara offered him some chocolates (despite first glance at distrusting before she reassured him), she did trap him and crushed his tail in the progress and took that fury out in forcing her to decide.
Cult Classic: By far one of the better adaptations of the story.
Jerkass Woobie: A few believe this, but the Mouse King, out of all people, may fit into this. He was abused by his mother, had his tail crushed many times, and even though he considers Clara his enemy, he still gave back the slipper when he could have just gone to the Nutcracker in sleep mode instead.
Moral Event Horizon: When the Mouse King threatens to kill Clara's kitten if she doesn't hand over the Nutcracker.
Nightmare Fuel: During the climax of the film the Mouse King comes back and attempts to kill Clara despite dying from a stab wound.
Bonus points as it implies that as he's blind with rage enough to likely not even know Clara is there and striking wildly with rat rage (despite him a mouse).
What an Idiot: The royal family don't notice the Mouse Queen transforming Hans into a nutcracker and just assume that he was a nutcracker right from the start and that Drosselmeier was trying to con them in some way.
The Woobie: Hans. He tries to save his uncle, Drosselmeier by breaking the princess' curse in order to save the latter's life. When he does do so, he's cursed into the form of an inanimate nutcracker by the spiteful Mouse Queen, with her son trying to hunt him down for crushing his tail accidentally. He is asleep for centuries till he's re-awoken to fight the Mouse King, completely unaware of the situation. When he finally defeats him, he's denied Clara's hand in marriage in the Doll Kingdom due to her own dreams. Thankfully, he's revived as a human being at the end of the film.