The dialogue between Chris O'Dowd and Maya Rudolph about their age difference was a rewrite by Jennifer Westfeldt. After casting Chris O'Dowd, the issue of the couple's age difference had to be addressed in the film.
Jason introduces Mary Jane to his parents (played by Kelly Bishop and Cotter Smith) in Mary Jane's dressing room, backstage at the Broadway revival of Chicago. In Kelly Bishop's real life, she appeared in (and won a Tony for) the original Broadway production of A Chorus Line, which in 1975 engaged in a famous box office and awards rivalry with the original production of Chicago.
The opening sequence that starts with a shot of the book The God Delusion by Richard Dawkins on Jason Fryman's (Adam Scott) nightstand was intended to end with a shot of the late Christopher Hitchens book on Julie Keller's (Jennifer Westfeldt) nightstand. A dilemma followed over whether the shot of Hitchen's book should stay in the film given the author's recent death. The shot of Hitchen's book was ultimately dropped due to time.