Many of the episode titles are names of songs from the 1940's. Whilst others such as 'Grief Encounter' are parodies of films of the era.
Emma Amos, who replaced Michelle Holmes as Yvonne, originally tried out for the part of Phoebe when the show first started.
In the DVD boxset commentaries, Derlva Kirwan revealed her agent encouraged her to leave the show to avoid being typecast as a "cheery Cockney". She stated that she later regretted the decision, adding that the same agent had encouraged her to leave Ballykissangel (1996) to avoid being typecast as a "stroppy Irishwoman... which happened anyway". Kirwan confirmed she would be interested in reprising the role of Phoebe in any revival, but felt that the role now belonged to Elizabeth Carling. When the show was revived for a one-off special in 2016, it was with Carling in the role.
The theme tune for Goodnight Sweetheart, can also be heard in the Star Trek episode "City On The Edge of Forever", during a scene in the 1930's.
Whatever era Gary finds himself in, he comes into contact with either Reg Deadman or a member of his family. In the opening episode, Gary gets directions from a PC Deadman, becoming confused later on when he meets Reg and he doesn't recognise him (having assumed the two men are the same person - unaware he has travelled through time). Gary later learns that the present day policeman is Reg's grandson and interacts with him several times, later learning that Reg is still alive in the present day and going to meet him. Additionally, when an error in the space/time continuum leads to Gary ending up in Victorian London, he is completely unsurprised to run into an ancestor of Reg's, who is also a policeman.