When Mrs. Armstrong calls Francesca "una staffetta", she means that she was a dispatch rider for the Italian Resistance.
Norman Parkis, the impaired stock man, is said to have spent some of his childhood at Blenheim Vale, an institution that is featured in the next episode, "Neverland."
In the closing credits, after the cast's names are listed, certain letters of some crew members' names are colored red. These letters spell out "Guy Fawkes," which is a holiday celebrated on November 5 with fireworks (and bonfires), as seen in this episode.
Morse mentions to Strange that things have "gone missing" from the evidence store - linking this story with the two previous ones in this season, which have both hinted obliquely that Morse's activities are now being closely and secretly monitored by Freemasons, just as Val Todd threatened in the first story, "Trove". However, it is significant that, despite his dislike of Freemasonry, Morse does trust Strange to "keep an eye" on things, even though he knows (and disapproves) of Strange's being a member of the order.
Joey Lisk is clearly an admirer of the title character in "Alfie" (1966), portrayed by Michael Caine. In the opening montage, he is seen buying a blazer similar to one Alfie wears in the film while spouting Alfie-esque opinions to himself in the glass. Lisk also sports spectacles similar to Alfie's.