Episode 23: Down the Hatch
Mickey and Goofy manage to shrink themselves and they end up being swallowed by Donald. Soon the two friends are inside his body and decide to cause some damage.
While this isn't the greatest Disney short ever made, there's no question that it contains some fast and fun action as well as a bit of imagination, which takes it a long ways. It was very fun seeing the two go through Donald's body from his heart to his head and even to his stomach where the duck plays a trick on them. Seeing the inside of his body do battle with the outside was very fun and made for some nice entertainment. As you'd expect the animation itself was extremely good with some great details inside the body.