The first few editions of the book had covers with a rising sun and a swastika side-by-side, sometimes dividing a map of the United States in half. Simple, direct, and to the point, right? But in the late 80s, after the release of the Cult Classic PKD adaptation Blade Runner, all of a sudden we get this◊. Although the book does mention that Nazi technology in space travel has advanced, nothing in the book even remotely suggests the San Fransisco of this alternate universe is the kind of cyberpunk metropolis Blade Runner popularized. In fact, when Tagomi crosses over to our world, it's suggested the San Fran of the book is even less industrialized.
A similar alternate history novel, United States of Japan, written by Peter Tieryas, is almost like The Man In The High Castle, even stating to be the Spiritual Successor of the said novel. While The Man in the High Castle puts a lot of emphasis in the Nazi-occupied America, this novel focuses more on the Japanese-controlled America side of things instead. It's also geared towards a younger audience since United States of Japan novel uses a lot of anime and manga tropes, more particularly, Cyberpunk and giant robots.
Reality Subtext: Philip K. Dick actually did consult the I Ching while coming up with ideas for the book, much as Hawthorne does when writing his. This may imply he is something of an Author Avatar.
Science Marches On: The mentions of Nazi colonies on Mars and Venus by 1962. Both the ease of getting to those planets, and the habitability of the latter, were overestimated in The '60s.
What Could Have Been: Dick toyed around with several ideas for a sequel, but he couldn't bring himself to do more research on Nazi Germany, which he found profoundly depressing and soul-draining enough for one novel. Among them were:
California Doubling: Inverted in that all of the scenes set in California are actually shot elsewhere. Seattle doubles for San Francisco in some scenes, as can be seen with what is clearly the Smith Tower in the background of the first episode. British Columbia doubles for such locations as the Colorado Rocky Mountains and the Catskills, and the small town of Roslyn, WA stands for Canon City, CO. The New York train station in Season Two is actually Pacific Central Station in Vancouver (complete with identifiably VIA Rail equipment on the tracks in one scene).
Fake American: Some American characters are played by Brits, including Rupert Evans (Frank Frink), Rufus Sewell (Obergruppenfuhrer Smith), and Burn Gorman (The Marshal).
Fake Nationality: Most of the Japanese characters are actually played by Americans: Cary-Hiroyuki Tagawa plays Trade Minister Tagomi, Joel de la Fuente plays Inspector Kido, and Louis Ozawa Changchien plays Kasoura; though Tagawa and Changchien both have some Japanese ancestry. Some German characters are played by other nationalities as well: Danish actor Carsten Norgaard plays the German Rudolph Wegener, and Australian actress Bella Heathcote plays young Berlin socialite Nicole Becker.
Follow the Leader: SS-GB is one for BBC, where the Nazis maintain control over the British Isles in a timeline where they won in the Battle of Britain campaign.
Jossed: Season 2 completely Josses the fan theory that The Man in The High Castle is Hitler himself.
Playing Against Type: Cary-Hiroyuki Tanaka is most well-known for playing villains, while here he plays probably the most sympathetic and likable Japanese character.
Troubled Production: There were plans to bring the book into a TV series much earlier by different studios but fell through, the BBC in 2010 and SyFy in 2013, before Amazon studios finally took over.