The various acts the cats put on to entertain Haru during the pre-wedding feast. It's especially hilarious when it cuts back to Haru either crying hysterically or looking completely uninterested the entire time.
Especially funny is when one of the acts gets tossed out the window and later, one of the guests gets tossed out the window too for laughing.
Haru's Imagine Spot of getting married to a cat. "I now pronounce you cat and wife."
"She's gonna rub this in my face, isn't she?"
And after that, when they learn that the cats holding up the fake walls had accidentally lined up like dominos. The Baron knocks them all down with one kick. Natori, meanwhile, groans over how stupid they were to do something like that.
"Was that a no?"
Combined with a Crowning Moment of Awesome for Muta: When the heroes are escaping the castle, Haru is worried that Muta is still stuck in the middle of the ballroom, surrounded by soldiers. A second later, the movie cuts to Muta swinging from a chain hanging from the ceiling, while the soldiers fall over each other trying to get at him. The Baron calmly notes that Muta's doing fine. After they escape, Muta catches up and is pissed that they didn't wait for him.
The king's craziness in general. One point in particular is when he declares that he will stop Haru from escaping by blowing up the tower. The chancellor freaks out, and then tries to stop him by insisting that he doesn't know where the detonator is. As soon as he says this, one of the king's servants cheerfully hands over the detonator.
Renaldo Moon is the greatest criminal in cat history, for having eaten all the food in the entire kingdom. Is there any surprise that it's Muta? Baron didn't take well to the news.