Although credited, Christina Hendricks (Joan Holloway Harris) and Bryan Batt (Salvatore Romano) do not appear in this episode.
The Group by Mary McCarthy is the book that Betty is reading in the bathtub. The book was released in 1963.
Lane: So we finally have an answer to the question 'What makes Don Draper smile?' Five thousand dollars seems to be the number.
Ken: I love getting telegrams, but I never send them.
Don: How is that supposed to help?