When Sam, Bobby & old Dean are outside Dean says " Sammy, when you get to be our age...", Sam says "Dean you're 30". In real life Jensen Ackles was 31 at the time and Jared Padalecki was 27. They both are 1 year older than the characters they play.
Hal Ozsan, who plays Patrick, is a Cyprus Turk raised in England. The chips that Patrick use have the Tunisian banner on them.
The language of the magic spell is Irish Gaelic.
The title of this episode is a play on the name of a 1922 short story by F. Scott Fitzgerald which was later adapted into the film The Curious Case of Benjamin Button (2008) featuring Brad Pitt and Cate Blanchett.
As Bobby and Dean are leaving the motel, Dean says, "Let's go, Ironsides." He is referring to the late 1960's TV police drama, Ironside (1967) featuring Raymond Burr as a former cop paralyzed after being shot in the line of duty.