The West Wing, which is much darker and more gothic than the rest of the castle.
The Beast's first full appearance, when he confronts and drags away Maurice.
The Beast when Belle disobeys him and goes into the West Wing. For the only time in the movie Belle seems to be in danger of actual physical harm from him.
The creepy spidery coach-thing that whirrs like an angry insect hive as it transports Maurice back to the village. You never see this thing again during the rest of the film. It makes you wonder where it's hiding.
Gaston suddenly stabbing the Beast in the side with a huge Slasher Smile on his face even after the Beast spared his life. If you pause the movie when he's falling to his death you can see skullsin his eyes.
That's nothing when you take into account the former option for Gaston's death: Apparently, when stabbing The Beast on the roof before falling off, he reacted while falling to his doom in a very similar fashion to Heath Ledger's Joker when Batman threw him off the roof in The Dark Knight.