Haigh meets the Hendersons at the seaside and comments "splendid weather for February!" (it was in fact 12 February 1948 when he killed them). He is then seen driving Archibald Henderson to his workshop down a road with trees in full leaf; this must have been filmed in May or early June.
In 1945, the widow Olive Durand-Deacon describes her husband as having served in "The Glorious Glosters". Although a common nickname for the Gloucestershire Regiment, it derives from their heroism at the battle of the Imjin River during the Korean War - in 1951.
Until 1963, the Sunday Mirror was called "The Sunday Pictorial", and therefore the news story about the disappearance of Mrs Durand-Deacon's could not have been reported by The Sunday Mirror in 1947.
The headline in the Sunday Mirror newspaper "Hotel Guest Missing" is from an edition dated 6 Feb 1949 regarding the "disappearance" of Mrs Durand-Deacon, but she didn't "disappear" until 18 Feb 1949, the same day she was murdered.