The producers convinced both the American & British governments to let them use real-life settings as filming locations for the series, including the still-recent American embassy (at Nine Elms) that opened in 2018. Britain allowed filming inside the foreign secretary's office, a rarely bestowed honour for any film or screen production, especially an American one. The one unavailable location was Winfield House, the American ambassador's actual residence. Although it's accurately described as occupying the largest plot of residential land (11 acres) in London aside from Buckingham Palace, the producers used a country house outside the city for filming purposes.
The Lenkov Group is a reference to the real life Russian mercenary Wagner Group and its leader Yevgeny Prigozhin.
The second time Rory Kinnear (Nicol Trowbridge) has played the role of Prime Minister. The first time was Prime Minister Michael Callow in The National Anthem (2011), the very first episode of the series Black Mirror (2011).
Prime Minister Trowbridge's character and ideology is somewhat similar to that of Boris Johnson who was the Prime Minister of the United Kingdom from 2019 to 2022.
Creator Deborah Cahn explained on an interview that S2 was shorter than S1 (6 vs 8 episodes) because Netflix gave her a premiere window and the way she saw that as possible was by doing less episodes. But then the streamer actually moved up the window, so she regrets the rush and made sure that S3 was again 8-episode long.