When Slack sends Lake out to find Harold and asks him to take a constable along too, Lake and the constable get up and move to the door but only Lake goes through - no sign of the constable who was walking behind him.
When Dr Quimper takes the old man's blood pressure near the end of the movie, he doesn't have the stethoscope earpieces in his ears.
Although the film takes place in October 1957, Alexander Eastley is reading the May 30, 1958 issue of "Eagle".
Although the film takes place in October 1957, the September 17, 1956 issue of "Life" is on sale at the Paddington Station newsstand.
The murder victim is shown entering a Third Class carriage on the train. The action takes place in 1957, but Third Class travel on trains was abolished in 1956.