Many of the close-ups of Jeff's hands during the series, were performed by Writer, Producer, and Director Charlie Higson, because Bob Mortimer's badly bitten fingernails were deemed unscreenworthy. According to Charlie Higson, "Bob's hands are not that attractive. Mine, however, are quite gorgeous."
Randall and Hopkirk have a very close relationship with the Doctor Who family. Besides Tom Baker being in every one except the first, there is at least one actor in each episode, who has been in either Doctor Who (1963) or The Sarah Jane Adventures (2007).
As a character quirk, Jeff Randall is a potato chip addict, even packing them to take on vacation with him.
The building, where the detectives worked, was called "Cope House", after the original Hopkirk, Kenneth Cope.
Actor Freddie Jones was also in an episode (Series 1 Episode 12) of the 1969 series that this show is a remake of.