This short was most likely inspired by the model train layouts that several of the animators had. Walt Disney himself had a miniature train that he could ride on, and even laid track around the studio lot for his miniature engine.
The trivia item below may give away important plot points.
'Out of Scale' marks one of the few cartoons where the picture ends with a mutual ending between Donald and Chip and Dale. Generally, most of the adventures would end with the Chipmunks getting the better of Donald, or humiliating him in some way or another.