Series creatives have said that Frank's artistic process in Season 3 was inspired by the abstract expressionism of the 1940s and 50s.
Over 110,000 Japanese Americans were interned at Manzanar between 1942 and 1945. In real-world history it was closed on November 21, 1945 and was designated a National Historic Landmark in 1985. In the alt-history it was liberated by the Japanese in 1945.
The armored car just inside the gates of the coal mine is a Soviet BRDM-2 and the tank inside the compound is a Soviet T-54. Both have been modified to appear more German.
In real-world history, Heinrich Himmler was Reichsführer of the SS. He was largely responsible for the construction and operation of the Nazi concentration camps that claimed the lives of millions of Jews and other civilians deemed undesirable by the Nazi State during the Second World War.
In the universe of "The Man in the High Castle", the Japanese do not operate under the same racial ideology as the Nazis, but legislation was passed to help align anti-Semitic laws amongst the ruling powers in North America. The enforcement of these racial laws is not uniform in the JPS, which makes Kido's execution of Frank's family in Season 1 especially cruel. That cruelty provoked Frank to plant a bomb at JPS headquarters in San Francisco at the end of Season 2.