Rachel Berry has a Wicked playbill on her vanity in her bedroom. Idina Menzel, who has a recurring role as Shelby Corcoran (the director of Vocal Adrenaline), and Kristin Chenoweth, who has a recurring role as April Rhodes, played the lead roles in the original Broadway cast of Wicked.
Sue says to Principal Figgins and Will, "and as soon as I figure out the difference between slander and libel, I'm filing a lawsuit". This is an obvious reference to a "Goof" posted under Sectionals (2009).
The trivia item for Kings Island misinterprets the line. The line as spoken as "I'll be in Ohio tomorrow chairing a benefit for Save the Rainforests at Kings Island." Olivia will be chairing a benefit for the organization Save the Rainforests and the event is occurring at Kings Island. It's possible it could be a joke as the original item suggests and the organization is trying to save a rainforest at an amusement park in Ohio. But that relies on the viewer knowing that Kings Island is an amusement park and thinking that there is a rainforest in the USA let alone one in Ohio.
Jesse's t-shirt in the first part of the episode says "utgång", which means "exit" in Swedish.
Olivia Newton-John in her phone conversation with Sue Sylvester (Jane Lynch) talks about saving the rain forests at Kings Island -Kings Island has no rain forests as it's not remotely tropical--it's an amusement park in Mason, Ohio.