Pooh Moon is a play on words (Blue Moon). However, the characters never refer to a blue moon but frequently refer to a "Honeymoon."
Caws and Effect is a play on the phrase "Cause and Effect."
While the relative size of the characters is pretty inconsistent in the series, we get a good sense of the size of Piglet. When Piglet jumps in the picnic basket full of corn, he appears roughly the size of an ear of corn.
In the segment of "Pooh Moon", Christopher Robin, Eeyore, Owl, Kanga and Roo are absent.
In the segment of "Caws and Effect", Christopher Robin, Eeyore, Owl, Kanga, Roo and Gopher are absent.