The network leased and refurbished as disused hospital for the program. The lower and upper floors of the hospital are used as other sets and production offices.
JD's father's final line when he asks JD to pull his finger and then says, "I pooed a little," was totally improvised and Zach Braff had to bite the insides of his cheeks to stop himself laughing.
Ted's "Band" is in fact, "The Blanks" a group the actor formed with his friends at college.