'Castle' trivia and fun facts

The actress who plays Ryan's wife in the show, Juliana Dever, is Seamus Dever's (Ryan's) real life wife.

In almost every episode, Castle makes a reference to "The Godfather"

Nathan Fillion, Jon Huertas, and Seamus Dever are the only actors who appear in every episode.

Detective Kevin Ryan (Seamus Dever) could be seen carrying a copy of one of Castle's books at least once in every episode.

According to Andrew W. Marlowe, Nathan Fillion read with 125 actresses to find the perfect Beckett.