In the scene in which "all the DJs" appear for the first time, the other DJs are only shown from behind. This is because if their faces were shown they would be paid as featured actors rather than extras - ironically, a SAG union rule
Johnny, Venus and Bailey sing an excerpt from the song, "Look for the Union Label". This was a song made up by and sung by the International Ladies Garment Workers Union (ILGWU) in a series of television commercials to encourage Americans to purchase domestic-made and union-made clothing.