The man laughing in the background when Sam pies Dean is actually director and executive producer Robert Singer.
When going to the crime scene posing as FBI agents, Sam and Dean use the aliases "Singer and Kripke": the names of series' executive producer Robert Singer and creator Eric Kripke.
The title of the episode is a reference to the song "Carry On Wayward Son" by Kansas that is played normally at the beginning of each season finale. Season 1 is the only season where the song wasn't played at the finale, but rather at the episode before.
"Carry On My Wayward Son" was released on November 19, 1976 and the airdate for "Carry on" is November 19, 2020.
Sam and Dean repeat lines from the Pilot, in this episode. This episode... Sam: "I can't do this alone." Dean: "Yes you can!" Sam: "Well I don't want to" Pilot episode, when Dean is trying to convince Sam to join him in finding their Father... Dean: "I can't do this alone" Sam: "Yes you can" Dean: "Well I don't want to"