On Eminem's eighth studio album "The Marshall Mathers LP 2", "Brainless" samples the portion of the film when the clerk from the liquor store says his name in correlation to the white person who robbed the store.
The pivotal penis drawings were a 'bone' of contention with the MPAA, particularly the scene with young Becca holding an image of one of them. Producer Judd Apatow elaborated it was the subject of much legal wrangling, including how erect they could be, if veins could be shown etc. The actress playing young Becca, Laura Marano, however has a different picture to hold before they cut to the actual drawing. You can even see from the reverse that the drawing she holds appears completely different.
In a skit for the special edition DVD commentary Judd Apatow had his nine year old daughter with him. He asked that no one swear in front of her. Jonah Hill swore a number of times angering Apatow. After an "argument", Apatow left the commentary with his daughter.
According to the DVD commentary, the night that Evan (Michael Cera) describes to Becca early in the movie is "beat by beat" what Seth Rogen, Evan Goldberg and their friend Sam Fogell did when they were in high school.