Last acting credit of Danny Green as Lord Surrey before he retired in 1969.
Jeff's wooden-framed sofa is swapped for Jeannie's in this episode, presumably to make it more comfortable for Mike Pratt and Jan Rossini while they performed the frolicking and kissing scene in Jeff's apartment.
Jeff Randall's car is a Vauxhall Victor, registration number RXD 996F. When Jeff is driving along the Thames following the baddies, Marty sits on top of the car to get a better view. A signpost can be seen in the background which coincidentally reads "Vauxhall Victor" which is pointing the way to Vauxhall and Victoria.