Anti-Climax Boss: Yogoshimacritein. Despite all of his ramblings about his incompetent son, and his sucess at eliminating 4 of the Go-Onger, the Final Battle against him, both before and after the Industrial Revolution are extremely short, with his normal size failing to stop the three remaining member at destroying the power cog, and losing to the reunited team member, while his giant mode get curbstomped by Engine-Oh G-12 Finishing Move.
Awesome Music: A lot of tracks. Go-onger has a really nice soundtrack in general, but to specify:
Character Development: Quite a bit of it on the part of the Go-on Wings, who, as far as some western fans are conerned, had one of the most unliked introductory episodes but became some of the best characters in the end.
Evil is Sexy: Kegalesia. Period. The fact that her actress is a former AV * "Adult Video" star doesn't help matters. It's no wonder that she labels herself as "in charge of Gaiark's sexiness" whenever G3 Princess is around.
Saki's interactions with Miu are taken as Les Yay by some.
Memetic Mutation: In Japan, pictures/videos of Gunpei (or characters imitating his "Dash Dynamic!" pose) are almost unfailingly responded to with "Kakkosugiru ze..."* "Too cool..." in reference to Gunpei's final words to Gunpherd in GP Final.
Tough Act to Follow: Sentai fans weren't entirely on-board with this season, primarily because it came after Gekiranger (Which is loved by Western fans). Speaking of Western fans, many who watched it after RPM weren't fully on-board with the direction taken.