“I have a very long and somewhat self-centered speech here, but I’d like to set it aside. Because this honor doesn’t just belong to me; I wouldn’t be up here if it weren’t for some very important people in my life,” he says, and thanks his family and his “other family.” “I was under a misapprehension that my accomplishments were mine alone. Nothing could be further from the truth. I have been encouraged, sustained, inspired, and tolerated, not only by my wife, but by the greatest group of friends anyone ever had.”
Cosmologist Stephen Hawking made a short guest appearance in the fifth-season episode; in the eighth season, Hawking video conferences with Sheldon and Leonard, and makes another appearance in the 200th episode. In the fifth and sixth seasons, NASA astronaut Michael J. Massimino played himself multiple times in the role of Howard's fellow astronaut. Bill Nye appeared in the seventh and twelfth seasons.
When Leonard receives a braggy Christmas letter from his brother, he feels bad about how little he and Penny have achieved in the past year. Leonard wonders if he and Penny should be thinking about the next step after two years of marriage, like buying a house or having a baby. Penny tells him she wants to do all those things someday, but she has a bunch of stuff she would like to do first.