Spot the Pineapple: a pineapple design can be seen on Gus' speedos, and a pineapple slice can be found in Boone's drink.
When Peters & Boone are confronting Shawn & Gus in their car, an exchange occurs where Shawn says "Ring the bell" and Gus says "Ding ding" and he looks at Boone, played by Carl Weathers. This is a clear reference to the final scene from "Rocky III"/first scene from "Rocky IV" in which Rocky and Apollo are sparring. Carl Weathers played Apollo Creed in the "Rocky" franchise.
When Floyd says "it's not a ghost it's a man" it is reminiscent of Dillon saying "it's not a lizard. It's two or three guys at most" in Predator. Both characters were played by Carl Weathers.
Every time Don and Boone are seen pulling out of the parking lot, they parked in reserved spots. The first of which being "Det. C. Lassiter" and lastly "Chief K. Vick"; both reserved 24 hours daily.
Peters repeatedly refers to Shawn as "Rick," meaning "Ricky Nelson." Nelson was a teen idol and rock and roll singer, first gaining fame starring in "The Adventures of Ozzie and Harriet" (1952) with his real-life family. He and Shawn (James Roday) look remarkably similar.