Star Trek: Errand of Mercy

Notes & Trivia

 * "Errand of Mercy" is one of only a handful of episodes that DeForest Kelley does not appear in.


 * First appearance of the Klingons on Star Trek. The Klingons will go on to become one of the more recurring and popularly known adversaries within the Star Trek mythos.


 * Actors Bobby Bass, Gary Combs and Eddie Paskey are all uncredited for their participation in this episode.