The Chevrolet that the prince and his new bride were travelling around in displayed faded paintwork, but at the time the event was taking place, it would have been a new car.
When husband and wife arrive in the blue sedan at the Palapye Hotel, Rosamund Pike looks to her right and observes a man and woman being seated at a table outside the hotel. She then looks to her left and the same man and woman can be seen walking toward the hotel with a hotel porter carrying their bags.
In the scene when everyone is listening to the radio, Ruth is supposed to be pregnant. But she is wearing a dress, with her waist just showing by her elbow, that she wore in an earlier scene when she was not pregnant.
At about 1'17, the civil servant refers to the new Prime Minister as Sir Winston Churchill. He was not knighted until 1953.
The Times front page was shown with a headline.However at this time the front page only had advertisements.
When Ruth returns to the UK (1952) she flies out of Bechuanaland in a DC3 (Dakota) which is probably correctly logo'd as Suid-Afrikaanse Lugdiens (SAL). She arrives at Heathrow in the same. By 1952 Suid-Afrikaanse Lugdiens (SAL) were using either DC4 Skymasters 1946 onwards or Lockheed Constellations 1950 onwards (more likely). The connecting flight after the DC3 was most likely with South Africa and was Jo'Burg, Nairobi, Khartoum, Rome, Heathrow.
The opening of the film takes place in 1947. The radio announcer says Indians will go to bed as subjects of the Queen, and will wake up to a new day (meaning a new independent state). Queen Elizabeth didn't ascend to the throne until 1952, her father was the King in 1947.
One of the British bureaucrats says that South Africa wants to annex "Botswana". At the time the story is set, it was known as the protectorate of Bechuanaland. It wasn't until 1966 when it gained independence that the name "Botswana" was used.
The Chevrolet sedan being used is a 1949 model. Thus, it wouldn't have existed yet. It is clearly stated that the action takes place in 1947.