If Magis had survived, he would've become this Sentai's green warrior, just like his actor did six years before…
The Cast Showoff: Epic 11 gave Moune's actress a chance to show off her cheerleading skills. She is part of the idol group Canary Club, whose repertoire includes cheerleading.
Dawson Casting: A tie-in booklet for Shinkenger vs Go-onger gives the Goseigers' ages, which leaves 18-year-old Kyousuke Hamao playing 21-year-old Agri and 20-year-old Kento Ono playing 24-year-old Hyde. However, the trope is played straight with 20-year-old Mikiho Niwa as 17-year-old Moune.
Jossed: Due to the fact that his helmet is never shown on-screen, there were quite a few debates about what Gosei Green's mech and animal would've been, with theories including it being a turtlenote this came from a combination of the fact that Mystic Brothers, which had his color, could've only been his had the egg been from a turtle, as well as the fact that Goseiger had shout-outs to Dairanger, which had a turtle mech. With the release of the Lost Ranger Key Set, his animal has been officially confirmed as a dolphin.
A more specific example: Datas was excised entirely for Power Rangers Megaforce, which is only possible because his combination with Gosei Great is to form the back of Hyper Gosei Great. For the toyline, Bandai of America released the three sets of Headers with motorcycles which replicated the backback created by Datas Hyper's legs.
What Could Have Been: The original plan for Goseiger called for there to be more of a rivalry between the different heroes, hence why they were split into different tribes ala Chou Sei Shin Gransazer. The Skyick Tribe (Red and Pink) would have been the idealistic straight heroes, the Landick Tribe (Black and Yellow) would have been closer to Anti Heroes and clashed with the Skyick Tribe a lot, and the Seaick Tribe (Blue) would have either been a Wild Card or a neutral arbitrator. While this was scrapped before the show even started (so the team pretty much gets along from the start), you can catch occasional glimpses of it from the way the characters interact with each other.
Although Goseiger was adapted into the first half of Power Rangers Megaforce, prior to Saban buying the rights to Power Rangers back and announcing Power Rangers Samurai, it was widely believed that if someone did buy the rights to Power Rangers back, Samurai Sentai Shinkenger, which ended up being adapted into the aforementioned Samurai, would've been skipped because of it's heavy Japanese roots. If Shinkenger had been skipped, Goseiger would've been the first season Saban adapted.