"Dwight, you ignorant slut" is actually a reference to classic Saturday Night Live (1975), when Jane Curtin and Dan Aykroyd were the Weekend Update hosts. Dan would often say to Jane "Jane, you ignorant slut!" It's fitting as SNL is a clear favorite of Michael Scott, a terrible improv actor and lover. Also, episode director Harold Ramis co-wrote and co-starred with Aykroyd in Ghostbusters (1984).
The hand movement used by Dwight Schrute to "shun," and then "un-shun" Andy Bernard was improvised by Rainn Wilson.
According to the DVD commentary, Greg Daniels thought of the scene where Jim and Pam try to talk Michael down from the roof as if Jim and Pam were a divorced couple, speaking in code to their child (Michael), which makes the new wife (Karen) feel "left out."
At the end of The Return (2007), Andy says he will complete his anger management training in 5 weeks instead of 10 by using "name repetition, personality mirroring, and positive reinforcement." When interviewed at the beginning of this episode, Andy says that he did, in fact, complete anger management in 5 weeks. However, in the end of the last episode Andy said that he graduated "on time."
The final appearance of Patrice O'Neal who passed away in 2011.