The t-shirt worn by Nico when he first appears in the Barnaby household bears the words "lebens, volens, potens" which roughly translates as "Ready, willing, able".
Prunella Scales Eleanor Bunsall is married to Timothy West who would appear as Marcus Devere in the previous episode Judgement Day (2000)
Cheryl Campbell plays Sandra MacKillop in this episode. She returns in episode 15.5, The Sicilian Defence (2013), in the role of Vivian Stannington.
Patricia Brake plays Anne Quarritch in this episode. She returns in episode 16.2, Let Us Prey (2014), in the role of Stella Spencer.
Sylvestra Le Touzel plays Linda Marquis in this episode. She returns in episode 13.5, Master Class (2010), in the role of Miriam Fielding.