Russian Rhapsody is a strange–and very funny–cartoon. First, as a historical document, it's a Hollywood cartoon mocking Hitler (before the end of the war and the extent of his atrocities became clear). In Rhapsody, he's an obnoxious windbag and there are a bunch of good jokes at his expense.
But once the first act is done–Hitler is going to fly a bomber himself to Moscow–Rhapsody takes a different turn. It's about the gremlins attacking the bomber. They're funny little creatures, destroying the plane in creative ways (though director Clampett never actually shows the specific effects of their sabotage) and they have a great song.
There are a lot of contemporary pop culture references; some still work, some don't. The Stalin one probably didn't work even back then if you knew anything about foreign affairs.
Until the final gag flops (it's another pop culture reference), Rhapsody is a very funny cartoon.
Directed by Robert Clampett; written by Lou Lilly; animated by Rod Scribner, Arthur Davis, Manny Gould and Robert McKimson; edited by Treg Brown; music by Carl W. Stalling; produced by Leon Schlesinger; released by Warner Bros.
Starring Mel Blanc (Adolf Hitler / Gremlin from the Kremlin).