These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
One of the lines in the song is "Ist ve not the supermen." Superman later on fights the Nazis.
Especially funny if you remember that Millenium in Hellsing were Nazi vampires (i.e. "supermen").
While Donald is assembling the small bullet-like shells, we hear this line in the song: "If one little shell should blow him (Hitler) right to *CLANG!*" Two years later: he commits suicide by shooting himself.
Memetic Mutation: The image of Donald Duck performing the Nazi salute with a swastika armband was very popular on Image Boards due to the sheer "what."-ness that it induced if you are unfamiliar with the cartoon.