Kurt sings the song "Cellophane" from Chicago. Chris Colfer sang the same song for his audition for the show.
Dianna Agron (Quinn Fabray) was the last person of the original cast to get a part. On her first day she had to do a scene with Cory Monteith (Finn Hudson) in which they 'made-out' together. Director Ryan Murphy told her to look sexy, but she was so nervous that she couldn't focus.
The band Kings of Leon was approached by Ryan Murphy about the use of some of their songs for Glee due to their uplifting message, but the band immediately told Murphy no and then insulted him and Glee online, leading to a lengthy public fight between the two parties where Ryan Murphy accused the band of homophobia and the band responded that they weren't and simply hated the show and would not be involved with it.
The night before shooting the pilot, Quinn had still not been cast. Dianna Agron auditioned and sang in the office next to Robert J. Ulrich the night before filming began.
The scene where Rachel reprimands Finn for deciding to quit Glee because his friends tease him originally ended with her slapping him. In her audition, Lea Michele reached across the table without any hesitation and slapped one of the casting directors, who was reading Finn for her. When the other casting directors erupted with laughter, Michele sternly told them "This isn't comedy - that was my sad face! Now, I'm going to do it again and you're all going to cry."