When Michael thinks Dwight has betrayed him to Charles (Idris Elba), he checks him for a wire in the parking lot.
Creed gets several of these.
In "Money" Creed reveals that whenever he gets into debt he dumps it all on his alter ego, "William Charles Schneider": Creed Bratton's real life birth name.
Furthermore, in "A Benihana Christmas", Creed can be seen singing "Spinnin' and Reelin'", a song by Creed Bratton.
In a deleted scene from "Booze Cruise", Creed talks about being the lead guitarist of the 1960's folk group the Grass Roots (best known for their hit "Let's Live for Today"), which Creed Bratton actually was. The finale outright confirms this connection.
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.
Paul Lieberstein, 7 episodes ("Money", "Two Weeks", "Gossip", "Whistleblower", "Sex Ed", "Training Day", "The Incentive")
B.J. Novak, 5 episodes ("Scott's Tots", "The Seminar", "The List", "Trivia", "Free Family Portrait Studio")
Steve Carell, 3 episodes ("Broke", "Secretary's Day", "Garage Sale")
John Krasinski, 3 episodes ("Sabre", "Lotto", "The Boat")
Rainn Wilson, 3 episodes ("The Cover Up", "Classy Christmas", "Get the Girl")
Mindy Kaling, 2 episodes ("Body Language", "Michael's Last Dundies")
Ed Helms, 2 episodes ("Christmas Wishes", "Welcome Party")
Brian Baumgartner, 1 episode ("After Hours")
Lieberstein has also been the showrunner since season 5, and many additional episodes have been written by cast members.
Edited for Syndication: In the TBS version of "Performance Review" Dwight wonders if the suggestion "Dont Sleep with your Boss" refers to "You boning Jan". In the syndicated version he says "You doing Jan".
Also, in "Sexual Harassment" Michael says "The only thing I am worried about is getting a boner", in the syndicated version he said "The only thing I am worried about is getting a shwing"
Episode 'Koi Pond' had its cold opening removed which involved a fake hanging by Michael and was also omitted from DVD release. Fortunately, the clip can still be seen on the official site.
Enforced Method Acting: Season's 2 "The Carpet" is centered around an incredibly foul smelling... "thing"... left behind in Michael's office. Unbeknownst to the rest of the crew, Steve Carell had thrown a stink bomb into his office just before shooting began on the scene in which the employees smell the odor in his office. Unless they postponed filming, there's a good chance that everyone's reactions to the smell, especially Kevin's, as Michael locks him in his office for a short while, is not acted.
Another moment, also courtesy of Steve Carell, is his incredibly awkward kiss with Oscar in "Gay Witch Hunt". He was only supposed to kiss Oscar on the cheek, but in that one take, Carell just wouldn't let go of Oscar Nunez (who plays Oscar) and kept coming closer and closer. Oscar trying to pull away was completely real. In fact, they had luck the camera kept fixed on Michael and Oscar (and that Nunez managed to keep a straight face), because the rest of the cast were all cracking up.
Executive Meddling: The reason why the pilot episode is an Americanized version of the British pilot episode.
Going into the 8th season, there was some meddling with Michael/Deangelo's replacement. NBC apparently wanted Catherine Tate to replace them, and James Spader to replace Jo Bennet, with more frequent appearances. Only the second one went through.
Fake American: Idris Elba (Charles) is actually British. The character seems vaguely transatlantic, especially in terms of accent, and anyone who's seen The Wire knows Elba could have done a much more convincing American accent if he'd wanted to. Charles is also an avid soccer fan.
Marathon Running: When cable channel TBS secured the rerun rights to the show, they made a habit of airing four or six episodes in a row one day a week, instead of one episode a day. This lead to a lampshading on an episode of Futurama... the Planet Express ship is converted to a passenger ship. When one passenger gets upset at the inflight entertainment provided by Dr Zoiberg, she yells "Turn down the lights and put on four episodes of The Office!"
That joke could also reflect the fact that many airlines show Office episodes as in-flight entertainment.
Throw It In: Many instances, especially in the talking head segments. There's always a complete script, but once the written dialogue has been shot, the actors are free improvise if they wish to do so. According to Word of God, Rainn Wilson particularly likes to improvise, noting, "Rainn has never not given an alternate version."
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.
One item of interest is that Adam Scott and Kathryn Hahn were considered for the roles of Jim and Pam, respectively. They'd go on to play political rivals and later boss (her) and employee (him) on Parks and Recreation.
Written By Cast Member: Paul Liebestein, Mindy Kaling and B.J. Novak were on the writing staff from the beginning. Steve Carrell later wrote "Survivor Man" and Season 2 finale "Casino Night".
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.