Jared Harris and Kiernan Shipka have been upped from recurring status to starring roles.
Although credited, Aaron Staton (Ken Cosgrove), does not appear in this episode.
Roger: My uncle lost his leg, hitching a trailer. He used to ask me to scratch his toes. He didn't have any.
Pete: We're the scrappy upstart.
Don: You don't say that to the clients do you?
Peggy: (to Don) You know something. We are all here because of you. All we want to do is please you.
John Slattery and Matt Long starred together on Jack & Bobby which aired on the WB from 2004-2005. Jessica Pare (who joins the cast later in the season) also starred on that show as Slattery's daughter.
Freddy Rumsen has left JWT (J. Walter Thompson) and has brought the client, Ponds with him. Ponds was indeed a client of JWT.
At one point, Peggy Olson and Joey Baird address each other as "John" and "Marsha" in cheesy, soap opera-like acting tones. This is a reference to Stan Freberg's 1951 record "John and Marsha", a parody/satire of over-the-top soap opera acting.
Candace: One of the boys killed in Mississippi, Andrew Goodman, he was from here.
Andrew Goodman was one of the three American civil rights activists who were murdered in Philadelphia, MS in 1964 by the Ku Klux Klan.