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 Star Trek: The Apple (1967). Spock (Nimoy) saves Kirks's (Shatner) life in latter.