— Will, who still seems to think he's the main character, starts an all-male acapella group with several dudes who are no longer on the show.
— Victor Garber shows up as Will's dad, and then we immediately forget that that ever happened.
— Cheerios coach Sue Sylvester enlists her three top cheerleaders, Quinn, Santana, and Brittany, to infiltrate the glee club in order to destroy it for some reason.
— New Directions briefly hires rival club Vocal Adrenaline's choreographer, named Dakota Stanley, in a subplot that we do not have any recollection of.
— Kurt comes out to Mercedes after a bunch of nonsense where Mercedes flirts with Kurt and then believes they are dating. He tries to reject her kindly, but she still busts the windows out of his car, if only to have an excuse to sing "Bust Your Windows."
— Sandy says the line "Who is Josh Groban? KILL YOURSELF." Josh Groban shows up to give Sandy a cease and desist letter.