The incident in the opening scene, in which executives at Young & Rubicam throw water on "Negroes" who are protesting on the street below was based on a real event that occurred on May 27, 1966, and which was covered on the front page of the New York Times on the following day. The scene in the episode was taken almost exactly from the Times account, including the dialogue between the Y&R executive secretary and the outraged protesters.
The song that Megan (Jessica Paré) sings to Don at his birthday party, "Zou Bisou Bisou," is a French novelty hit first recorded by Gillian Hills in 1960. Some non-French-speaking Mad Men viewers mistakenly thought the lyrics they were hearing were nonsense sounds ("zooby zooby zoo"), but "bisou" means "kiss," so the song's title means "Oh, Kiss Kiss!" and is also referenced in that episode's title, "A Little Kiss, Part 1." Paré's cover of the song was released both digitally and on vinyl.
Due to a disagreement between creator Matthew Weiner and AMC the production of the fifth season began later than usual. The show didn't return for summer (2011) but months later in spring (2012), resulting in a long break between seasons 4 and 5 and no new episodes in 2011.
Seasons 5, 6 and 7 were greenlighted simultaneously, as part of the deal Matthew Weiner made with AMC during their famous fallout of 2010/2011, which delayed the production for more than a year.
This was the first episode of Mad Men to be shot digitally. Prior to season 5, Mad Men was shot on film.