On their way, Sheldon (Jim Parsons) talks about meeting George Smoot. Leonard (Johnny Galecki) is reading a book, "Wrinkles in Time", which Smoot co-wrote with Keay Davidson.
George Smoot had written to the producers of the show and requested to be featured on the series. Smoot, who received Nobel Prize in Physics in 2006, is an admitted fan of the series. The scene involving Smoot was shot at the Warner Brothers Studios in Burbank, California on February 18, 2008.
Most broadcasts of this episode in the UK cut Dr. George Smoot's only line, because it refers to crack.
Penny tells a friend that she only has one shot to play Anne Frank in a one-night play. Kaley Cuoco, who plays Penny, has previously played Anne Frank in the 8 Simple Rules (2002) Season 2 episode Merry Christmas: The Story of Anne Frank and Skeevy (2003).
In a future episode during a flashback, the guys mention Firefly (2002) as being a show they would sit down and watch together via the roommate agreement. Summer Glau played River Tam on Firefly.