Michael, being Michael Scott, overreacts to an 'injury' he has. This steers everyone away from realising that Dwight is the one with a more serious injury. No matter how ill or injured you are though, if you call shotgun, you get the front seat, no matter what...at least according to Michael. Written by
Did You Know?
This episode is B.J Novak's (who plays Ryan, and is a writer for the show) favourite episode of The Office. See more
In the hospital the ER doctor orders Dwight a CT. Later the nurse advises that all metal needs to be removed and won't allow Michael in the CT room until he looses all metal on his personage. This wouldn't be necessary for a CT which uses X-Rays and is not magnetic. The only metal that would hinder the procedure is metal that would show in the actual image. For the example of a head scan, earrings would need to be removed.
Furthermore, the actual procedure done on Dwight is in an MRI machine which would react with metal. See more
I wanna clamp Michael's face in a George Foreman grill.
References Forrest Gump