Hooker (William Shatner) saves McGuire (Leonard Nimoy) from being shot by a criminal. McGuire's reply is "I owe you one, Hooker". Hooker then replies "I remember I saying the same thing to you 17 years ago". This is a reference to The Apple (1967). Spock (Nimoy) saves Kirks's (Shatner) life in latter.
People in this episode who have appeared in other things with William Shatner: Heather Locklear in Boston Legal (2004), Leonard Nimoy in Star Trek (1966), and Richard Herd in SeaQuest 2032 (1993).