Reference to scene where a druglord appears to be a fan of the protoganist that is an author of novels
Castle calls Greg's bringing back his supposedly dead girlfriend 'very Pulp Fiction'.
Castle refers to finding our "zihuatanejo" when looking over love letters from one person to another in prison. Castle then tries to explain what it is but Beckett's seen the movie.
Castle makes a number of references to "McDreamy" and "McSteamy". Both are nicknames for characters in Grey's Anatomy.
Druglord's from the 80's name is Calderon.