Tim Warner's ass is padded to give the impression that he indeed just sits on his butt all day and draws.
The opera song Tim is listening to as he paints is actually, in fake Italian words, recalling the plot of the movie. Lyrics include "Who is Lance? He no stop me. I be Walt Disney, I be Burger King, I be Warner T." Lyrics written by Daniel Matz.
Lance Gold makes an appearance at the book signing and threatens to kill Tim.
Brian is wearing a bandage on his wrist in his final declaration to the camera. His character tried to kill himself. In a scene cut from the film, you find out he killed his cat "Squiggles" as a tribute to "Silver Lining" ending.
Many customers in the book signing scene were not actors but actually customers who walked into the comic book store and agreed to say a few lines on camera.