"Tomorrow is Yesterday" gave me the giggles. I love how Spock's scanner turned into a spinning circular Rebel flag.
I like the voices he used, for Spock and Sulu especially, and Backus' "It's the only way to fly" is even funnier if you remember that it was also Western Airlines' tagline at the time Star Trek
's original run.
Also liked the use of the Tijuana Brass' Casino Royale
theme for "The Immunity Syndrome".