The blue Morris 1800, registration OTM 168M, which Det Supt Pettiford drives when he takes Haskins home, was also used in Thou Shalt Not Kill! (1975) as the car in which Wands and Monk initially escape from the bank siege. It is recognisable by the distinctive handwritten letter "O" on the front registration plate.
This episode leans to a more comedic side, and whenever the smart alack bad guys are shown, jovial Scott Joplin style piano plays. Also, at the very end, Regan, with a lollipop in his mouth, says "Who loves you, baby," like Telly Savalas as Kojak.
First appearance of Doreen Haskins. She is played by Anne Stallybrass. Sheila Reid plays her when she appears again in Victims (1978)
The script had to be altered to explain George Layton's black eye. Shortly before filming, he had been hit by a motorist in a road-rage attack as he was being driven home.
Philip Madoc (Detective Superintendent Pettiford) previously appeared with John Thaw in Rough Justice (1966)