The audiobook that Ernie listens to in his car, "The Prague Paradox" by L. Marvin Metz, is narrated by one of the show's producers, Paul Giamatti. This uncredited appearance was deliberately set up as an Easter Egg for season 2, in which Giamatti recurs as eccentric author Metz.
The vehicle Dud drives is known as the Volkswagen "The Thing" (United States), whose popularity reached its peak in the 1970s. Wyatt Russell (Dud) is the son of Kurt Russell who starred in The Thing (1982). It was first created in the 1940s as a staff car made for General Rommel aka "The Desert Fox"; they didn't overheat, and the air-cooled motors were perfect for warmer climates. They were also used in the popular TV show "The Rat Patrol (1966)" by the Germans.
Lead character Dud (Wyatt Russell) is frequently compared to Jeff Bridges's character in The Big Lebowski (1998), who preferred to be called "The Dude". Russell has said that he's flattered by the comparison, but he and the producers are quick to point out that the similarities are fairly superficial, largely the result of Dud's outward appearance. Dud doesn't smoke weed, and the story begins with him in a transitional phase, having recently lost his lifelong career as a result of his father's death. Unlike The Dude, who forever goes with the flow, Dud is extremely optimistic, looks for purpose, and aspires to become something greater.
Wyatt Russell has repeatedly stated in interviews that he's hopeful that he'll have the opportunity to play Dud again one day. Creator Jim Gavin has said that he's open to wrapping up the story as a film.
Wyatt Russell (Dud) received a copy of the pilot script several years earlier, and he fell in love with it. When the show was greenlit, creator Jim Gavin and showrunner Peter Ocko learned that Russell was interested in it, so they set up a meeting at Patrick's Roadhouse diner and arrived to find two homeless men sitting on the curb talking. They quickly came to the realization that only one was homeless, the other was Russell. The three men clicked, and no one else was considered for the role.