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
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.
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