Corrected entry: During the first dance number, when Chad is dancing with the cheerleaders in the hallway, all of the girls are not wearing any shoes but instead they are dancing in socks.
Correction: So what? If they want to dance in socks, there's no particular reason why they shouldn't. We're talking about a reality where people spontaneously break into song and carefully choreographed dance routines. Under those circumstances, frankly, pretty much anything goes.
Correction: It was most likely to twirl easier on the floor they were on in the scene, as the choreography includes multiple one-foot spins.