Most measurements are given in metric, used in Germany since 1876, however when Luther is trying to escape at the metro station his height is given in feet and inches and his weight in pounds.
In the movie's alternate reality, the Nazi Empire is called Germania and the city of Berlin remains as such. Actually, according to Hitler's plans, Germania would be Berlin's new name, and occupied territories would not form an empire, but to become Germany's "Lebensraum" (Vital Space).
Shortly after her arrival to Berlin, the American journalist is seen walking on the street with a row of Nazi flags waving on the other side of the street behind her. These flags are seen showing the obverse, since the hoist is on the right side. However, the swastikas on the flags appear pointing in the correct direction instead of the "Z" shape that should have been seen.
While driving through the city you see in the back a Peugeot dealer. The logo seen was used from 1980 till 1998. The signing on the outside with the blue and yellow stripes was introduced in the mid 90's.
In the movie intro a billboard is shown on the side of the road with the German word beßßere which doesn't make sense because the letter ß already represents double s.
At the 14-minute mark, a poster is shown with the title "Peace and Prosperity: The Fuhrers Promise". This is grammatically incorrect. It should read "The Fuhrer's Promise".
The film begins with the Allies defeated at Normandy in 1944, so this is where reality parts company with Historical fact. Although later on there are several references to Heydrich still being alive, whereas in reality he was assassinated in 1942 by Czech Patriots, it is stated in the original novel by Robert Harris that Heydrich survived the attack. This aspect is particularly important because the novel deals with the Gestapo killing the attendants to the Wannassee Conference and therefore the architects of the Final Solution, with Heydrich being the one actually orchestrating the murders.
Several propaganda wall posters downtown Berlin have inscriptions solely in English language (Elliot taking a picture with MacGuire in front of one, another one when MacGuire takes a cab to her secret appointment). Although it would be highly questionable that a German government, self-confident with the victory over the allies, would approve such all-in-English posters in the German capital, the novel explains this by the fact Hitler wanting to show a more open face to United States, as he is desperate to strike the an alliance against the Soviet Union.
The 'Mercedes-Benz' that Hitler arrives with is actually a Rolls-Royce Silver Cloud 'camouflaged' with Mercedes Star emblems at the front and on top of the radiator grill.
When March is questioning cadet Hermann Jost at the gymnasium, there is a basketball hoop in the background. Since basketball was associated with United States, it seems odd to have it in the training headquarters of the SS, a quintessential organization of a Nazi government.
The bus which takes the reporters from the airport into Berlin is far too new. The movie is set in the 1960s, this type of bus first appeared in the late 1970s.
Several city views prominently reveal the movie was filmed in Prague, although set in Berlin.
When March enters the "Reichssicherheitshauptamt" after the field inspection at the lake, it's the new building of the National Museum,
with the old building in the background. Furthermore the towers of the Teyn Church are visible in the background, when the coach with the newsmen arrives downtown.
Several times through out the movie it is mentioned that six million Jews died. Since Germany won WWII in the film, the Nazis would have been able to complete the extermination of Europe's Jews the number of victims would have been approximately 12 million.
In the frame the Gestapo builds for their murders against the Wannsee conference attendees it is mentioned that one of them was shipping art to Switzerland to hide it there. Clearly on the map in the intro of the movie Switzerland is part of Germania. Therefore hiding something there doesn't make a lot of sense. (However, on the map in the original book Switzerland appears outside of the boundaries of Germania.)