Here's why:
* Goldfish on Stilts: The short features a scene with goldfish in a bowl, which are balanced on stilts and walk around.
* Guy with Umbrella Head: The main character in "The Old Mill Pond" is a frog who wears a large umbrella as a hat.
There might be other cartoons with similar elements, but "The Old Mill Pond" is the most iconic one with these features.