This is the story of the engineer Casey Jones and his insane efforts to make sure he delivers the mail on time. The train sequences are very goofy--a major plus.
This cartoon short from Disney is well worth seeing but I must warn you about two major distractions--the singing and, more importantly, the narration by Jerry Colonna. As for the singing, my feeling is many will like it and just as many won't. But the narration--that is something many, many will struggle with, as Colonna's shtick was to deliver his lines in an ear-piercing manner. It's a shame, as other than that it's a cute little cartoon...with VERY annoying narration.
By the way, look carefully at the scene where the conductor jumps off the train. Despite this, in the next scene you can STILL see him standing on top of the train!!