Action takes place around February 21, 1965, the day Malcolm X was assassinated--Peggy mentions that "Malcolm X was shot last Sunday."
Hollywood's legendary Musso and Frank Grill doubles as many different bars and restaurants (including Sardi's) on the show. In this episode it's used twice - as the bar where Pete's father-in-law spills the beans, and as the restaurant where Pete and Ken have their confrontation.
While filming this episode, Jon Hamm asked Matthew Weiner if Don Draper could sink any lower. (His decline and depression forms an arc in the first half of the season.) Weiner convinced him that Don would get his mojo back soon.
After telling Freddy he was old fashioned for thinking all that women want is to get married, Peggy tries on Dr. Faye's "engagement" ring during the Ponds focus group, and admires how it looks on her hand. Don catches her and smiles, and Peggy quickly takes it off.