As Chen (the waiter at the Chinese restaurant) leaves Sheldon (Jim Parsons), Leonard (Johnny Galecki) and Raj (Kunal Nayyar)'s table, he mutters "Young idiot" under his breath in Cantonese.
The FULL version of the "Nighty-night" rhyme:
Nighty night,
Sleep tight,
Don't let the bed bugs bite,
But if they do,
Take your shoe,
And break their little heads in two.
The waiter in the Chinese restaurant (Chen) is played by James Hong, the same actor who played the host of the restaurant in the classic Seinfeld episode, The Chinese Restaurant (1991). Hong also played a brief part in Blade Runner (1982), the movie that Howard wants to take Leonard to later in the season in The Peanut Reaction (2008).
Leonard and Sheldon have two different copies of Halo 3 (2007) as the box Leonard is holding did not come with the Master Chief helmet on the desk. The Legendary edition's box cover is different.
This episode was watched by 9.68 million people with a rating of 3.7 (adults 18-49).