Mr. Mouse Takes a Trip (1940)

"Mickey Mouse and Pluto hit the road - and run into trouble."

Mickey is heading out on vacation from Burbank to Pomona, taking the train. The conductor, Pete, won't let him on with Pluto, so he hides Pluto in his suitcase, and tries to hide him all throughout the trip without much luck. But Pete wins when Pluto is hooked by a mail hook. Or does he?