In a change of pace for TV cops, when Bradford talks about moving to New York, Sergeant Grey accurately tells him he'd have to start over and attend the NYPD academy, then be the John Nolan of the NYPD. Usually, TV cops are shown transferring from one coast to the other seamlessly.
The actor who plays Deputy Sharp at the correctional facility is Don Swayze, younger brother of the late Patrick Swayze.
Under the Gun (2010), a Season 3 episode of Castle (2009) used the same title. That show also starred Nathan Fillion. In addition, the writers of this episode, Terence Paul Winter and Elizabeth Davis Beall, along with series creator Alexi Hawley, were writers on Castle, with Hawley writing the Castle episode that has the same name as this episode.
Early in the episode Nick Armstrong tells Elvis Grimaldi that the incident they are entering is like playing chicken with a runaway train, on fire, filled with zombies. Harold Perrineau (Armstrong) was in the first episode of Z-Nation and the film "28 Days Later," both zombie films.
The office shooting scene appears to take place in a redressed set first used on "Boston Legal" (2004).