When they're filming the dog food commercial, Susan's cigarette disappears from one shot to the next as she's leaving.
When the Germans enter the village their vehicle has the emblem for the 2nd SS Division "Das Reich", the number plates are Wehrmacht however.
Darwin (Gielgud) states that he was in "Djakarta". However, the name was "Batavia" until independence in 1949.
The film shows a television commercial being filmed at a time when there were no commercials on British television.
Queen Elizabeth II's coronation was in 1953, yet the flag display in the background includes the Canadian "maple leaf" flag which was not adopted until 1965.
Queen Elizabeth II's coronation was in 1953, yet the flag display includes the flag of Guyana, which wasn't designed until 1962 or officially adopted until 1966.
In the apartment of Susan and Alice there is a floor lamp looking like the famous Arco designed by Achille Castiglioni. That scene is happening in the 1950s, whereas Arco was designed in 1962.
In the night time scene on the bridge wit Susan and Nick, after she's told him she wants to have a child with him, even though the time period is supposed to be early 50s the vehicles passing in the background are clearly contemporary.
When Sir Leonard Darwin is shown writing his resignation over the Suez debacle, the paper has the letterhead of "Foreign and Commonwealth Office". The Suez Crisis took place in 1956 and the Foreign and Commonwealth Office did not come into being until the 1968 merger of the Foreign Office with the separate Commonwealth Office.
In the scene where Meryl Streep and Charles Dance meet for the first time in her apartment in England, after he removes her coat and the camera starts a slow dolly in (right after she says "A commute on the cross-channel ferry"), a wheel of the dolly is visible in the reflection of the painting of the cherubs on the wall.