Continuity mistake: In the final scene when Miss Pierce in a car asks Foyle to get in, she looks rather more presentable initially with her hair in curls partly framing her face, with noticeable red lipstick and possibly make up. When Foyle gets in the car and takes up the conversation, the hairstyle reverts to her usual dowdy plain style off the face and the lips are natural.
Factual error: The episode takes place in 1946. Numerous scenes are shown in which the public buildings are clean. In 1946 they were soot streaked and grimy black and white from generations of coal fires and pollution. In addition one street scene has a street sign on a pole with a modern graphical notice on it rather than a worded notice of the time. Also, in the same scene the street name plate has a rather updated type face.