Alternate Character Interpretation: Was Totenkopf the actual mastermind of his ultimate plan? Did his machines turn against him before he died? Did they murder him? Was he sane to begin? Considering how little is shown about him and his plan, those questions have no answer.
Big Lipped Alligator Moment: The miniaturized elephant in the kidnapped scientist's laboratory is never brought up afterwards, as despite the clonation stuff in his island, Totenkopf is never implied to be interested in mini-size lifeforms, and the purpose of that experiment remains unexplained.
Fridge Brilliance: The idea that Dr. Totenkopf, who has been dead for 20 years in the story, is being portrayed using re-cut archived footage of Laurence Olivier, who had died 15 years before the film is released. The idea of a dead man portraying a dead man just kinda seems to work.
Fridge Logic: In a minor case, Joe refers to "World War One." At the time the film is set, the sequel hadn't broken out. It would have been called "The Great War" (or "The World War", which was used at the time, although mostly by Germans).
Actually, World War One was being referred to as such prior to the outbreak of World War IInote though extremely rarely, and mostly by people wanting to make a point — and even then "the first World War" was more common (capitalization deliberate — the usual point was that it had been the first of a new kind of war, a World War if one will, rather than that there'd necessarily be another one). As the Zeppelins seem to be headed by Germans but not Nazis, one might assume that in this universe, World War Two was a conflict not started by the invasion of Poland (although the East Asia war probably happened/is happening, given references to Tojou Hideki and Manchuria).