I did not find the Man in the High Castle to be very plausible, I thought the show was overall implausible; however, the few aspects of the show I did find plausible was the damming of the Mediterranean, the architecture of Germania (former Berlin), and how the Japanese empire does not hold a candle to the power of the Greater German Reich. Japan had no chance of winning WW2, as the United States naval and industrial power outmatched theirs they had no chance of taking the U.S. mainland. Not only was Japan fighting a grueling sea war, they were also fighting China and Chinese allies. Put the allied powers of Australia, New Zealand, and India into the equation and you get a bad scenario for Japan. In Man in the High Castle, Japan is seen as a weak, backwater, corrupt nation on the verge of collapse. This would be accurate if Japan won WW2.
