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 mentions that Nazi technology in rocketry 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: British Columbia for such locations as the Colorado Rocky Mountains and the Catskills.
Fake American: Several Brits play Americans, including Rupert Evans (Frank Frink), Rufus Sewell (Obergruppenfuhrer Smith), and Burn Gorman (The Marshal).
Fake Nationality: Americans Cary-Hiroyuki Tagawa (Trade Minister Tagomi), Joel de la Fuente (Inspector Kido), and Louis Ozawa Changchien (Kasoura) play Japanese characters (though Togawa and Changchien at least have some Japanese ancestry). Danish actor Carsten Norgaard plays the German Rudolph Wegener.
Jossed: The cast and director mention in several interviews that the identity of The Man in the High Castle is not revealed yet. Which puts down the theory that Hitler is the man himself. Unless, of course, we're dealing with a Lying Creator.
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.