Theresa's line "It's hard for a 28 year old to get Prom." is an in-joke to both Ben McKenzie and Navi Rawat being in their late 20s when this episode aired.
Trevor's line to Marissa "I don't buy that phony English accent for a second." is an in-joke to Mischa Barton. She is actually British, so her accent would have been accurate.
Ryan has no visible bruising after getting in to a major fight the night before.
Volchok repeatedly calling Ryan a "little bitch" is a callback to Premiere (2003) . This is what Ryan's brother Trey calls him, also right before they steal a car.