In the manga, Usagi and Mamoru officially got married at the end of the series and Usagi became pregnant with Chibiusa, which officially began the second era of the Silver Millennium into the prosperous kingdom of Crystal Tokyo. In the anime, however, they simply get back together.
This is the series finale, as well as the 200th episode of the series.
Usagi's voiceover at the end of the episode was an almost identical callback to her introduction in the first episode.
The writer, director, and animation director to this episode were Ryota Yamaguchi, Takuya Igarashi, and Katsumi Tamegai respectively. Coincidentally, the three of them worked together in the first episode of this last season.
This was the only episode of the final season to feature an appearance by Princess Serenity.