This story provides some hitherto-unrevealed backstory for the Morse character and his family. It is now disclosed that Gwen was not merely his father's second wife, but "the other woman" in an adulterous relationship and that their marriage was hastened by her being pregnant at the time with Morse's beloved half-sister Joyce. Joyce does not appear in "Scherzo", but Gwen reveals that she is "living in sin" with a man named Garrett. In the "Inspector Morse" story, "Cherubim And Seraphim" (1992), set more than twenty years after "Scherzo", Joyce, there played by Sorcha Cusack, was specifically referred to as "Mrs. Garrett", and her husband Keith also appeared briefly as a character.
This episode sees Lynda Rooke returning in the role of Morse's unpleasant stepmother, Gwen; she was previously seen in the last episode ("Home (2013)") of Series One, set almost six years earlier than this one.
When taxi driver Joe North drops off the complaining harridan Gwen Morse at her stepson's house, he refers to her jokingly as "Clytemnestra" - a perhaps rather surprising reference to the queen of Greek myth who murdered her husband Agamemnon.
The confrontation with the clearly corrupt Commander Dury brings to mind a genuine London police scandal at the beginning of the 1970s, when charges of corruption were successfully brought against a number of police officers, many in the Vice Squad, who had been taking lavish bribes from the underworld.
Every season of "Endeavour" has one story whose title is a musical term. A scherzo is defined as "a lively movement", usually the second section of a symphony or sonata. In this case, the title may be seen as ironic, as this "lively movement" includes three gruesome murders, a violent beating and a suicide. It is also, of course, the second of the three stories in this season.