Ryan Devlin returns as Dalton, last seen in Season 4 Episode 3 (Brainless in Seattle Part 1) dealing brains to Don E and Blaine for their restaurant, Romero's.
When Al (Gage Golightly) first meets Blaine, she mentions that she interviewed Ty Griss, the CEO of a company called You-Freight-EZ. The Tigris and Euphrates are two connected rivers in the Middle East.
One of the chapters is titled "Mystery Machine". The title card comes up as the camera pans to a panel van in an underground carpark. The van's silhouette similar to the van in Scooby-Doo, which was called the Mystery Machine