After one of his fantasies, Castle asks Ryan to say "boyo" with an Irish brogue. The scene was written that Ryan only said it once; the back and forth volley of "boyo"s between Castle and Ryan was ad-libbed by Nathan Fillion and Seamus Dever.
Chad Everett was battling lung cancer while filming what would be his last screen appearance. He died six months after this episode aired.
In the 1947 flashbacks, Vera planned to escape from Tom Dempsey when Dempsey and his gang would be distracted by a prize fight being broadcast on the radio, featuring an Irish boxer named Jimmy Doyle, who was taking on Sugar Ray Robinson for the Welterweight championship. This was a real boxing match, famous for being the first title fight in which a fighter died; Jimmy Doyle died from a brain injury in the hospital after being knocked out. Interestingly, as was later discovered, he was not actually Irish, but a mixed-race Creole man named James Emerson Delaney.
Mark Pellegrino, Chad Everett Charles Malik Whitfield and Ellen Geer have all appeared on Supernatural (2005).