The royal Hertfordshire regiment is a fictitious regiment. It did exist as a territory army regiment but ceased to in 1961. It is now known as the royal Anglian regiment since 1964.
Darren Morfitt has played two different characters over the course of the series:
- Episode 20.4 Discovery: Part 2 (2017) - DCI Andy Steemson
- Episode 20.3 Discovery: Part 1 (2017) - DCI Andy Steemson
- Episode 14.6 First Casualty: Part 2 (2011) - Sgt Jason McDermott
- Episode 14.5 First Casualty: Part 1 (2011) - Sgt. Jason McDermott
Kieran Bew has played two different characters over the course of the series:
- Episode 14.6 First Casualty: Part 2 (2011) - Lt Stephen Lockford
- Episode 14.5 First Casualty: Part 1 (2011) - Lt Stephen Lockford
- Episode 8.8 Body 21: Part 2 (2004) - Stephen Wiltshire
- Episode 8.7 Body 21: Part 1 (2004) - Stephen Wiltshire
The bridge near where Cats' body is pulled from the river is the "Richmond Lock and Footbridge".
Tom Ward (Harry Cunningham) & David Ajala (Mark Blakefield) also worked together on episode 2.1, Murder on the Plantation (2013), of Death in Paradise (2011) as Alex Seymour & Louis Nelson respectively.