The song played by Sheldon in the car is Greensleeves.
The title refers to the vegetables of the family Brassicaceae (Cruciferous vegetables) that include cauliflower, cabbage, cress, bok choy, broccoli and similar green leaf vegetables (such as Brussels sprouts, which Sheldon eats in the episode).
One of three episodes where Sheldon (Jim Parsons) wears shorts; the others are episode 1.4, The Luminous Fish Effect (2007) and episode 5.17, The Rothman Disintegration (2012)
There are multiple Wizard of Oz references in this episode. First, when Sheldon says don't pay attention to the man laying in the bed. Second, when they call Steve Wozniak the great and powerful Woz.