Factual error: Reference the rural scenes. In the 40s, barley fields did not exhibit large perpendicular tracks made by crop sprayers.
Factual error: At the end of the film, Tom Jericho makes his way to the "Adelphi Hotel" in Manchester. The outside of the Adelphi building just off the Strand in London is used.
Factual error: Kate Winslet and Dougray Scott drive through a field of the crop, rape. This crop was not grown during the second world war.
Factual error: At the beginning of the film, as a British Admiral (or senior naval officer) leaves Bletchley he returns a salute. Although a naval officer, he does not give a naval salute but rather a half hearted army salute.
Factual error: The scene of 1946 London - Trafalgar Sq. looking south down Whitehall. You can see the turrets of the new MP office building - put up only a few years ago.
Factual error: A scene labeled as being from 1951 shows a name (Nook) having been typed on paper and then being whited out by a substance similar to Liquid Paper. Liquid Paper wasn't invented until 1956 in an American kitchen and wasn't marketed, and the patent applied for until 1958. (00:20:01 - 00:20:25)
Factual error: In the opening scenes the staff car door is opened by a four-ringer Wren (Deputy Director, very rare) equivalent to Royal Navy Captain, instead of a rating.
Chosen answer: This is not a mystery. Claire "stole them to read them" as Tom Jericho told Hester. As he later explained to Wigram, she had taken the messages to give to Puck who had the means to decipher them, and who was looking for his missing brother. The Kestrel traffic from ADU contained the names of victims of the Katyn Massacre. However, Puck and Claire were surprised by the imminent reappearance of Tom, and suddenly fled, explaining why some messages were left behind.