When George (Jason Alexander), Jerry (Jerry Seinfeld) & Elaine (Julia Louis-Dreyfus) are dancing to the Michael Jackson song "Don't Stop Til You Get Enough," we see them do 'the swim' down a hallway. This isn't a clip from any episode - it's an outtake from the final episode that aired directly after the clip show on NBC.
This episode aired immediately before the series finale. An outtake of the cast dancing between takes during the filming of the finale is featured here.
In the version of Green Day's "Good Riddance (time of your life)" used in this episode, its tempo is a little faster than the normal version of the song.
Jerry (Jerry Seinfeld) speaks to the camera, breaking the fourth wall, during the opening scene, while Kramer (Michael Richards), Elaine (Julia Louis-Dreyfus), and George (Jason Alexander) are down the hall on their way to the movies, and are still entirely in character yelling at Jerry, worried that they'll miss the previews.