A well-worn item within UFO circles is that flying saucers are in fact classified military technology and that they may be a development of supposed Nazi efforts (or, in many versions of the story, outright successes) in producing and operating aircraft capable of staggering feats of aeronautics. These tales sometimes invoke the mythical substance "Vril" or other fantastical concoction that allows the saucers to supposedly operate as they do.
The problem with all of these tales is that we actually have a very detailed (though not always quite comprehensive) account for the history of technological development, and nothing indicates that the Nazi regime's scientists and engineers ever attained mastery of aircraft capable of the feats often attributed to UFOs. For the Nazis to have made such a quantum leap in design is at odds with the fact that they left no verified paper trail behind in the form of scientific publications, test reports, confirmed blueprints, etc. demonstrating the application of radically novel concepts of physics. No Germans absorbed by Paperclip or similar Soviet efforts to exploit Axis technological know-how after WW2 have ever come forward with physics that is both radical and demonstrable, though there have certainly been claims made by former engineers employed in the Nazi war effort that they "worked on" such-and-such flying saucer projects. It's the same old yarn: someone claims that they were part of a remarkable secret program, yet they can't put their super-duper advanced knowledge to use anymore or usher in any revolution in physics that passes the acid test of scientific peer-review. We can also note that German efforts to exploit nuclear physics for the purposes of producing an atomic bomb lagged far behind those of the United States, shackled by limited resources and Nazi bureaucratic bungling. To suppose that they were somehow able to produce aircraft that exploited, all the way back in the 1940s, what would today be considered radically advanced principles is to stretch credulity to breaking point. Furthermore, the Luftwaffe relied overwhelmingly on propeller-driven aircraft throughout the entirety of the war. Even though they made limited use of jets (largely to no effect) during the final phases of the conflict, it was a case of too little, too late. Reports of "Foo Fighters", sometimes attributed in UFO lore to German secret projects, would surely have included routine accounts of attacks by these craft by an enemy that was desperately throwing all it had at the advancing armies and air forces of the Allies. In other words, the behavior of UFOs during WW2 is not consistent with them being German creations, and for them to have been German creations from the 1940s (or even from the 1930s in some versions of the tale) is itself not consistent with how technology progresses.
We see the same problem with accounts by the likes of Philip Corso and others who have developed the theme that 20th century advances in electronics and aeronautics were really the result of reverse-engineering alien technology. Such stories are profoundly anti-scientific for the simple reason that they ignore the voluminous and readily publicly available documentation for the development of a multitude of technologies. They are also, unwittingly, rather insulting to the power of human ingenuity, which is relegated to the role of imitation rather than creation. To suppose that our high-tech advances could only have come about by imitating ET is ironic, however, since it still requires that the engineers were clever enough to decipher alien tech (pathologically, this alien tech is often simultaneously supposed to be "beyond our understanding" or "thousands of years ahead of our own"), which means that they were at least potentially clever enough to have come up with these technologies on their own. The narrative that they "had to" have copied alien tech, therefore, is obviously unwarranted. That's not to deny that countries and corporations take advantage of technology stolen from adversaries to give themselves an advantage and forego the costs of acquiring the desired level of technical mastery on their own. Shortcuts are always welcomed and can be crucial in cut-throat competition, but even here there are pertinent facts that count against the reverse-engineering hypothesis. In Thomas Rid's book "Cyber War Will Not Take Place", he relates how Chinese industrial espionage efforts are not quite as deleterious to the preeminence of American and Japanese industry as is often imagined. In order to reproduce something, it is not enough to simply obtain the blueprints. There is an entire nexus of human interactions necessary to any complex production process, and these often consist of unwritten rules and forms of cooperation that are not apparent in blueprints or actual hard copies of a pilfered device. Noam Chomsky once related a similar point about how aspects of the American strategic weapons program could just as well have been completely unclassified because Soviet manufacturing processes lagged far behind those of the United States. That is, even if the Soviets wanted to, they had no way of reproducing certain military components because the way they made things was not up to the task.
Some Nazi UFO stories have the Germans collaborating with extraterrestrials from Aldebaran, while others have them developing the saucer technology on their own. The latter is arguably more in keeping with white supremacist notions about the inherent "genius" of the "white race", though ET stories can also serve this role if it can be claimed that whites are descended from a super-advanced civilization hailing from another solar system.
Despite the logical and logistical problems, stories and myths abound about Nazi flying saucers and are often repeated breathlessly as though they had a solid basis in reality. Secret staging grounds in Antarctica are invoked, peopled by Nazi military refugees who escaped from Europe and set up shop in the southern continent. The Antarctic bases are imagined to be preparing for the establishment of a Fourth Reich and reflect an earnest longing by the authors of these tales for the re-establishment and eventually triumph of Hitler's vision. "Aryans" from Aldebaran are imagined to be waiting to join forces with their earthly Germanic brethren/descendants to usher in a new order once a racial-spiritual signal is received for a revival of the cosmic struggle. See the book "Black Sun" by Nicolas Goodrick-Clarke for more details about this deranged mythology.
Not all neo-Nazis spout these sorts of myths, nor are all the people who spout them neo-Nazis. Nevertheless, they have served as a means by which fascist currents have established a foothold within ufology and the paranormal, and even when not used for overtly fascist ends, they still contain implicit messages about the "inherent genius" of the "white man". There is no doubt that Germany did possess radically advanced weapons designs and concepts during the war, but they were not alone in this, and many of these designs were not viable as instruments of war given the limitations of technology at the time. As alluded to, the implementation of high technology was as much hobbled as it was facilitated by the Nazi regime, which spread its eggs too thinly among too many baskets, thus diluting its already scarce resources (the Nazis were notorious for this, and a particularly grotesque manifestation of this tendency was the squandering of resources to the implementation of the Holocaust, even while the German military was on the ropes in the field of battle. Of course, for the Nazis, the "Jewish Question" was not separate from the military one).
The following appeared in the comment section of Joe Rogan's interview with Bob Lazar in 2019:
Did you notice a glaring contradiction? American forces are reputed to have lost to German saucer-equipped forces thousands of miles from Europe in "New Swabia" shortly after WW2 - yet the Germans couldn't inflict similar defeats using flying saucers during WW2 in Europe?
"Anti-gravitics" is a popular trope in UFO lore and has been doing the rounds for decades. One can hardly avoid running into it when watching vintage UFO-themed documentaries and TV specials from the 1970s and 1980s. The problem presents itself again: if the Germans were so far ahead in physics and were able to implement break-through concepts that would today be considered super-advanced, how were they nonetheless unable to produce an atomic bomb?
And of course, we have the obligatory "World Government" trope rearing its ugly head. This is of course inspired by the motif of "World Jewry" and "International Bankers" pushed by the Nazi propaganda machine. It has also insinuated itself into narratives about the "New World Order", similar to how "Cultural Marxism" is a mutation of "Cultural Bolshevism", another Nazi talking point. The NWO trope has gained currency on both the far left and the far right, and one does not need to be a neo-Nazi to repeat it. These themes are rich with transmogrifying potential - but, I would argue, they are all the more insidious for that, because constantly repeating a worldview that aligns with and is integral to fascist epistemology, while having an element of plausible deniability and mutability, can thereby reinforce fascist thinking by dint of repetition and a seeming validation of its tenets (not insignificantly, repetition is itself an integral instrument in the Nazi ideological tool kit, and neo-Nazis will hardly be averse to seeing their opponents do the work for them).
The commenter was of course correct in stating that our governments are keeping big secrets (as though that was a secret), but not being privy to them, he must indulge in fantasies that invoke a complete abandonment of the realities of logistics and material science. This is quite typical of UFO mythology and exposes the magical and irrational epistemology that underlies much of it.