The excerpt Gail reads Joel is from Chapter 24, The Pavilion of "The Three Musketeers" by Alexandre Dumas (,Père), a novel written in 1844.
Just like the opening scene of episode 1.2, this episode begins with Marcela in a discussion with her psychologist. Pieces of the conversation are even repeated.
Richard Cordery and Jason Hughes both appeared in Midsomer Murders (The Made-to-Measure Murders s13e2).