Near the episode end, Deborah Burns has overdosed on pills she saved from medications administered to her while hospitalized. When her lifeless body is discovered, medical staff try to revive her using manual chest compression. That technique was not widely known until the sixties, a time after the setting of WPC 56. It was first described in the article 'Closed-chest cardiac massage,' JAMA. 1960;173:94-97 and came into common use some time later.
Although the series is set in the West Midlands, the large-scale map of Brinford that is seen in the police station, showing the locations of various attacks on women, depicts the area around Starbeck, between Harrogate and Knaresborough, in North Yorkshire. Various alterations have been made to the map, including a "factory" placed rather implausibly on top of a railway line.