Even the musical theater stuff is switched up.
Santana, who has moved to New York and is staying with Rachel and Kurt, is suspicious of Brody; she initially believes he is a drug dealer, but later discovers he is a male escort, and gets Finn to come to New York and confront Brody.
A week later, she was cast as Brittany.
Puck later gets into academic trouble, but realizes he needs to graduate after meeting up again with his high-school-dropout father, but he fails a crucial test that will keep him from graduating with the rest of the seniors.
While Blaine was initially a recurring character, Criss was promoted to the main cast for the third season.
He is approached by during "Homecoming" about the possibility of joining the New Directions, but he declines, saying he shouldn't have to join a stupid glee club just because he is openly gay.