When Poole is being helped from his cottage to return to duty, he rebuffs Fidel, telling him "I'm not dead yet." That line is from another British endeavour called Monty Python and the Holy Grail (1975).
Actors Sean Gallagher, Shirley Henderson, and Don Warrington were all on Doctor Who (2005) in series 2.
Don Warrington and O-T Fagbenle played father and son in the miniseries "The Five".
Both Kieran O'Brien and Gary Carr both have been on the TV show Bluestone 42 (2013). Carr in season 1 and O'Brien in Season 2.