Defictionalization: Famous props in the show like Dwight's bobble-head of himself and Michael's "World's best boss" coffee mug have been made into merchandise that fans can buy.
Not only is there Dwight's bobble-head, there are bobble-heads of the whole main cast available.
In "Business Ethics" Michael mentions viewing a YouTube video called "Cookie Monster sings Chocolate Rain". You'd think a video like that would have already existed on YouTube but it didn't. A video was created by a fan after the episode aired.
Will Arnett was seriously considered for the part of the next boss for Dunder Mifflin but was turned down as there were concerns that his new series would conflict with the schedule.
This article shows a few more actors who auditioned, including Seth Rogan for Dwight and John Cho for Jim.
Several The Daily Show alums have appeared on the American version of the show. There are the obvious stars Steve Carell and Ed Helms, but also Rob Corrdry, Beth Littleford, Rachael Harris, and the aforementioned Wyatt Cenac have had minor roles or were reoccurring characters.