Revealing mistake: Dialogue in the episode specifically mentions the A2 and A282 roads near Dartford, Kent - the actual roads used were the A1 Barnet by-pass, Galley Lane and Well End Road. The error is revealed by the sight of a road sign that appears just as the Austin Princess Limousine turns on the the main road - the sign shows that the car is not turning on the the A2/A282 near Dartford, but the A1 at Barnet some 40 miles away.
Trivia: When Jeff Randall goes to the "Glasgow Tenement" (just after the opening title sequence) watch the graffiti on the walls behind him. One piece of graffiti shows the "stick man" logo from "The Saint", over which is is written the words "IS BENT". This was an in-joke by the crew of Randall & Hopkirk (Deceased) as, at the time (September 1968) they were filming back-to-back episodes of "Randall & Hopkirk" and Roger Moore in "The Saint" at Elstree Studios - even to the extent of using the same props and scenery.
Trivia: Mike Pratt (playing Jeff Randall) really was laid up in a hospital bed with two broken legs. Mike Pratt was attempting to climb a drainpipe in a slightly inebriated state during his 38th birthday celebrations. He fell 20 feet into the basement area. He'd forgotten his keys, and saw the stand-in doing it - successfully - first. Mike being Mike, he thought, "I can do that" and had a go. Jeff's 'in character' excuse in the show was that he'd fallen from a balcony in a chase - a little more dignified than the truth.