The series suffered from the BBC's lack of a proper archiving policy until it audited its archives in 1978. It was BBC policy before then to wipe master tapes and reuse them for other programmes, thereby saving money and storage space. From a full tally of 799 episodes, 466 (broadcast between 1962 and 1974) are thought to no longer exist. Additionally, some colour videotaped editions only survive as monochrome film copies. The final four seasons, broadcast between September 1974 until September 1978, exist in full.
Before he became famous as a movie star, Michael Caine turned down Jeremy Kemp's role of Police Constable Bob Steele, as he did not want to be typecast in a television series.
The "Z Cars" theme (traditional folk tune "Johnny Todd") proved so popular that Liverpool-based football team Everton F.C. immortalized it as their theme tune as the teams enter onto the field, a tradition which remains. In 1964, Watford F.C. adopted the tune, as it was their then manager Bill McGarry's favourite television programme. Long-term series actor James Ellis (Bert Lynch) was quick off the mark in releasing his own single of the tune in 1962, on the Philips label (PB.1230).
Elisabeth Sladen appeared in three episodes of the series. Producer Ron Craddock subsequently recommended her for the role of Sarah Jane Smith in Doctor Who (1963). She retained fond memories of the series, saying in 2009: "I loved Z Cars. If you see a clip of it now, it still holds up incredibly well - really good actors, great directors, and flying by the seat of your pants. You kept on learning, and there were always places for you to learn, which there aren't so many of for young actors now."
The Ford Zephyrs used in the black and white episodes were actually primrose yellow. This colour showed up better on screen than actual white, due to the vagaries of the monochrome TV cameras.