Throughout this episode, many characters make reference to Rachel's nose being a result of her Jewish heritage (an antisemitic stereotype), and contrast it with Quinn's perfect nose. However, in their real lives, Dianna Agron (Quinn) actually is Jewish, while Lea Michele (Rachel) is not (she was raised Catholic).
The Gaga shirts read as:
Emma - Starts with "Ginger", ends with "OCD"
Will - "Butt Chin"
Brittany - "I'm With Stoopid" and an arrow pointing up at her face
Santana - Starts with "Bitch", ends with "Lebanese" (meant to say "Lesbian")
Rachel - "Nose"
Kurt - "Likes Boys"
Mercedes - "No Weave"
Mike - "Can't Sing"
Finn - "Can't Dance"
Sam - "Trouty Mouth"
Artie - "Four Eyes"
Puck - "I'm With Stupid" with an arrow pointing down at his pants
Quinn - "Lucy Caboosey"
Tina - "Brown Eyes"
Lauren - "Bad Attitude"
In this episode, Santana says "If you look in the mirror and don't like what you see..." This is also a lyric from The End. by My Chemical Romance, a band featured earlier in the season and mentioned in a previous episode.