Besides the comic-book superheroics, an interesting thing about some of these old Superman cartoons is the role of the narrator. They all begin with a voiceover from an unseen narrator who introduces the general concept of Superman, of course, but I'm talking about a character as narrator. In the original "Superman" (1941), Lois Lane was the storyteller; the film we saw was or became the story she wrote as a reporter for The Daily Planet. In this one, "Showdown," Lois takes a back seat to Supes and his alter ego--or double--Clark Kent. Added here is another doppelgänger for the man of steel in the form of a crook impersonating him (as, meanwhile, his crime boss impersonates Edward G. Robinson).
The short doesn't conclude with a story by Lane, either, but with Kent waking up from a snooze. One may read this as him continuing his impersonation of not being Superman, but another way to look at it is that the entire story of doubles (Clark/Superman and two Supermans) was Clark's dream after a boring night at the opera. In this final scene, Lois says she has a story to tell him, but we never hear it. This is Clark's story.