After Prince Charming learns that a girl who fits the slipper has entered the castle, he heads towards the foyer with a beaming smile, which quickly fades to disappointment when he encounters Anastasia instead of Cinderella.
And when Fairy Godmother and Anastasia start fighting over it, a spell is accidentally fired, and hits Lucifer— a Beat, and he walks out from behind Lady Tremaine, now with his head on the body of a duck. He takes a look at himself, aand gives off a mix of a yowl and a quack.
The scene where Lady Tremaine causes the glass slipper to fit on Anastasia.
Footman: It fits! Grand Duke: It fits?! Anastasia: IT FITS!
The Prince initial reaction upon meeting Jaq and Gus, once he gets over, well, meeting them.
Drizella: Oh! Somebody put out the cat! Anastasia: Lucifer! Hold still! Stop! (she repeatedly smacks Lucifer with a pillow, then swats him with it, sending Lucifer flying face-first into the wall. He slowly slides down and smashes a vase on the cabinet, the water inside finally extinguishing his tail)
After performing an impressive stunt to get aboard the ship carrying Cinderellanote including getting thrown by his horse out of a window, sliding down a rope and safely onto the ship, the Prince actually pauses for a moment and looks around him, as if thinking: "Wait. Did I really manage to do that?"
"But the talking mice say she's the wrong girl!" It Makes Sense in Context for us right away, but just imagine how that must have sounded to the King.