At Springfield Community College, there is class on TV writing being taught by a Professor Harmon and voice by Dan Harmon. This is a reference to Dan Harmon, the creator of the NBC/Yahoo show "Community." His story circle mirrors his career path, and at the end, he is shot with painballs as a callback to one of the most popular "Community" episodes.
When the men in white suits leave the truck after shooting Chang, one of them says, "Red leader, standing by"; another says, "Blue leader, standing by"; and a third says, "Red 5, standing by."