Mickey is the operator of a personified steam engine, or "choo-choo". While watching this cartoon, the train reminded me immediately of Casey Jr. from Dumbo. Though the two characters are separated by about 12 years, I just find it funny how they both act similarly. More than likely the characters are based on the train from "The Little Engine That Could" (a good example of this will be discussed later in this post) which is why they seem alike.
In any case I found it interesting.
Another funny coincidence is this dog, a playful friend of Mickey at the train station. Am I crazy for pointing out that the character looks like a primitive Pluto? This dog even has that familiar bump on its head like Pluto, not to mention a similar bodily form. Officially animation historians cite The Chain Gang as the toon which introduces the character that eventually evolves into Pluto, so I'll agree with that; however, I'll always see this dog as a distant cousin of the famous yellow pup.
Like I said, Mickey's Choo-Choo develops Mickey's and Minnie's personalities a little more by allowing them to converse with each other. While this may not sound that important, consider that in previous cartoons the pair never really talked to each other. Instead they either sang or pantomimed everything. In this toon they exchange a few words and their first real conversation is held.
Mickey asks Minne to play a song on her fiddle (the same instrument she carries in Steamboat Willie) and we get to hear a rousing rendition of "Look Away, Look Away, Dixieland".
Whenever Mickey and Minnie go into one of their song and dance routines in these early shorts, it's interesting to see how the characters use their environment. Mickey especially has a habit of using nearby objects and animals as musical instruments.
One gag I like is when Mickey uses the floorboards of the train depot as a giant keyboard. It reminds me of the playfulness in a classic scene with Tom Hanks from the movie Big. Totally unrelated, but interesting nonetheless.
That example I mentioned earlier that tied Mickey's choo-choo train and Casey Jr. to the train in "The Little Engine That Could" is this scene they all share. All three trains have trouble climbing a steep mountain, and all three trains manage to overcome their struggle.
Unfortunately for Minnie, the caboose unlatches from the train with her on it. A great POV shot follows with Minnie atop the runaway car going through tunnel after tunnel.
Thrown in for good measure is a great gag that I've always enjoyed in any cartoon where something fast goes by stationary characters that lose their clothes (or feathers as the case may be).
Along the way, Minnie and the caboose find a cow on the tracks. In a gag that is reminiscent of the "gochig" one from The Plowboy, the petrified cow runs into a tree (along with the caboose) and is squashed.