First appearance of the new Denton "Central" Police Station, which is used until the end of the series. The previous building in Leeds was sold and soon demolished. Interestingly, the first novel, "Frost at Christmas", refers to a new station being planned for Denton, but this never eventuates.
This episode is based on one-half of the recently released Frost novel "Hard Frost", the first written in five years.
First and only appearance of D.C. Burton, who was a prominent character in the Frost novels up to this point, making his debut in the second, "A Touch of Frost", as a P.C., who by the next novel "Night Frost" has transferred to C.I.D. The original series character of D.C. Mark Howard was based on him.
Final appearance of the Ford Sierra ("D843 MPP") that had been Frost's car since the start of the series.
The only episode when Frost is shown reading a national newspaper, as opposed to the (fictional) "Denton Evening News". It's near the end, as Frost is sitting on a park bench waiting to accost his suspect and his choice is "the guardian".