The second of two occasions where Tige Andrews and Michael Ansara were castmates, the two actors having separately both playing Klingons on Star Trek (1966), the earlier occurrence of their having worked together being in the live TV drama series Playhouse 90 (1956), in the episode The Killers of Mussolini (1959). Ansara would later reprise his Klingon role of Kang from Day of the Dove (1968), teaming with two other actors who played Klingons in the original series--John Colicos (Kor from Errand of Mercy (1967)) and William Campbell (Koloth from The Trouble with Tribbles (1967), also having played the non-Klingon character Trelane in The Squire of Gothos (1967))--when the three legendary Klingons would join forces in the sequel series Star Trek: Deep Space Nine (1993) in the episode Blood Oath (1994). Andrews, whose Klingon character Kras was not mentioned by name in the original series episode Friday's Child (1967) and did not survive the episode, never worked with either Colicos or Campbell.
Three of the guest stars appeared in the third and final season of STAR TREK. Michael Ansara (Ray) played the Klingon commander Kang in Day of the Dove (1968). Rex Holman (Eddie) and Ron Soble (Karl Schwartz) played brothers Wyatt and Morgan Earp in Spectre of the Gun (1968). And although he never appeared in the original Star Trek series, Ray Walston (J.B.) earned his sci-fi creds playing the title role on My Favorite Martian (1963).