When Rachel searches Santana's name one of the descriptions under a link says "Sex is not dating. Yeah if it was Santana and i would be dating" This is from Season 1 Episode 13 (Sectionals), the first hint of a Brittany and Santana romance.
At the start of the episode, a joke is made describing the Twilight books as "poop on paper". Later, Marley and Jake sing "A Thousand Years" by Christina Perri from the film The Twilight Saga: Breaking Dawn - Part 1 (2011).
The "Fondue for Two" intro changes: Brittany is no longer seen doing a half-splits jump with pompoms in the hallway.