Anvilicious: Mark Twain spent most of The Prince and the Pauper talking about the dangers of a legal system under the domination of the upper class. This is why the film incarnations are so much shorter (not to mention more timeless) than the book, because the adaptations cut out a great number of instances of brutal Tudor "justice" that the Prince encounters in his travels.
The Disney version:
Awesome Music: Even though it's less than half an hour, the music is spectacular. Especially the coronation theme (starts at 1:20).
Pete locks Donald in the dungeon along with the Prince, even though Donald had not done anything to get in Pete's way. This may seem like a typical Villain Ball thing, but it makes sense when you think about it. Donald is a close servant to the Prince, so it's likely that he could have figured out that the Pauper, disguised as the Prince, was a phony, and that would ruin Pete's plan. Donald either knew too much, or would have known too much.
There is very little time between the king's death at night and the "Prince's" crowning the next morning. You'd think the kingdom would need more time to mourn the loss of their king... except no, they wouldn't. After all, Pete led them to believe that the king had turned corrupt.
He Really Can Act: The film may only be 25 minutes, but Wayne Allwine utilizes them to really bring out the emotion in both Mickey and the Prince, especially in the scene where the king dies.
is spectacular. Especially the coronation theme (starts at 1:20).