He might have gone to Argentina then to the south pole and then from there flown out in the vimana aircrafts. Or maybe he went inside the subterranean earth as entrances to such are located in south america, then emerged above the Antarctic as there is another entrance there and must be connected somehow. Or he was flown out of Germany in foo fighters from the start which the allies reported seeing flying away during the fall of Germany. There can be many theories and we simply do not know the truth because there isn't conclusive evidence.