Barry Smith drives a two-tone light blue / dark blue Jaguar S-type, registration DWD 606C. However this is not the same car as the one with the same registration which seen in the opening titles for Series 1-3: that car is all the same dark colour.
Warren Mitchell (William Wardle) previously appeared with John Thaw in Corporal McCann's Private War (1964) and later appeared with him in Ancient History (1997). Mitchell is best known for playing Alf Garnett in Till Death Us Do Part (1965) from 1966-1975, Till Death... (1981) and In Sickness and in Health (1985) from 1985-1992.
In this episode, Tony Allen (presumably playing Bill the Driver, as he does in many other episodes), gets out of the *back* of the Ford Consul, where Carter normally sits, as they go to visit Charlie Smith at his scrapyard. On this occasion, another officer is driving.
This edition was sixth in the charts with an audience of 7.8 million under the JICTAR Ratings System.
The three actors who played the Smith brother's, all later appeared with Dennis Waterman in Minder (1979). Godfrey James (Charley Smith) appeared in The Dessert Song (1980). Julian Holloway (John Smith) appeared in You Need Hands (1982). And Billy Hamon (Barry Smith) appeared in A Star Is Gorn (1984)