Between Season 2 and Season 3 of "The Man in the High Castle," the creative team wrote a sprawling, detailed document that charts how the US fell to the Nazis.
Season 3's Executive Producer, Eric Overmyer, wanted the Grand Palace in Denver to be like Rick's American Café in Casablanca - the central hub for the community, full of spies, remarkable for its faded grandeur.
George Lincoln Rockwell, here the Reichsmarchall for the American Reich, was in the reality time line the founder of the American Nazi Party in 1959. However, he served in the US Navy during World War II and was not a convert to Hitlerian ideas until well after the war. It is unclear how he rose to a position of such prominence in the High Castle time line, though presumably like John Smith he was co-opted soon after the Nazi conquest.
The creative team behind "The Man in the High Castle" only used archival film clips that would've been accessible in the alternate time-line to craft Hawthorne Abendsen's "first film" of the allies winning the war.
In the alternate history of TMITHC, the high school was previously named after Fritz Kuhn, former Reichsmarshall of North America, a fact that emphasizes the great impact Thomas Smith's story has had on the zeitgeist of the American Reich in Season 3.