When Sylvia tests her gun in an Italian meadow it mirrors the famous scene in Chacal (1973)which stars Emilia Fox's father, Edward Fox as a professional assassin.
For the uninitiated, "Volpe" is Italian for Fox, therefore Signora Volpe is Miss Fox, which refers to Sylvia Fox, played by Emilia Fox.
Both sisters have played a forensic pathologist . Tara Fitzgerald in waking the dead and Emilia Fox in Silent Witness.
In Episode 3 Volpe "breaks down" in her mini. The Policeman passing fixes it and tells her it was a loose spark plug. Problem is it's a Mini Cooper D. As in Diesel. So has no spark plugs!
In series 2 episode 1: after driving away quickly from the house in Santa Marinella to escape, Sylvia looks in the rear view mirror, but there is a curtain behind her in the campervan.