The season finale, where the "Hundred Animals" part of the show title proves to be more than just marketing. All ONE HUNDRED Power Animals show up to aid our heroes, with the help of Plex's concept art for unused Power Animals like the Mouse, Horse and Peacock etc.
Others from that movie include Yuusuke giving a super-powered Yabaiba a Curb-Stomp Battle, his later swordfight with Gaku, and Soukichi Banba revealing himself. And, of course, all ten heroes transfoming and the Dream Sentai pummeling the revived Orgs with Liveman's opening playing in the background.
Meta-wise, Episode 30. Even if it's undone via Deus ex Machina, you gotta admit, Toei had BALLS to write a scenario where the main team is killed off. We never see that anymore in future or past Sentai shows.