Minor bit of FB I just noticed in GaoGaiGar Final. One of the Big Bads, Pisa Sol, took the place of the repli-Trinary Star System's sun. How does it die? By being turned into light. Perhaps this qualifies more as Fridge Irony, but still.
It's only directly noted once, but all the replicants colors are fainter than their normal counterparts. Most obvious with Repli-Galeon, as his head and mane lack their traditional gold color. How is this fridge you ask? Well, given that none of the replicants can survive without the Pas-Q Machine, they could be considered paleimitations of the real things!
In the J-Ark's first appearance, it manhandles the 3 primevals and nearly destroys one of their cores with sinlge attack, and it wasn't even using full power. Why didn't they just destroy the core and prevent the Z-Master from ever returning? Since Mamoru uses Hell and Heaven to disintegrate the Z-Master core and that Kaidou would have have logically been able to do so also, using conventional weapons to destroy the core or even a piece of it would apparently backfire horrifically. This could even be the reason that the Red Planet lost the war, since if J and the J-Ark's strength is typical of their kind, and there was an entire legion of them, how could they have lost with such power? The theoretical event could have been thus: a primeval is destroyed improperly, with the backlash (perhaps a mass zonderization wave?) ruining any chance of the Red Planet winning, and the primeval in question is either replaced or restored by Liver afterwards.
As mentioned on the main page, there's a minor spoiler in the second opening, although only in retrospect. In the first opening, the part where they're singing about the G-Stone uses Mamoru's name to mean "protect". In the second opening, the part where they're talking about the G-Stone uses Kizuna's name to mean "bond". Even if you know Japanese or watch it with subtitles, you're unlikely to realise that's a name until you see her. The Fridge Brilliance kicks in when you realise that both times, they dropped the name of the most important non-combat character. In the first half, the Zonders would've been unstoppable without Mamoru there to purify them (he takes a more active role in the second half). In the second half, Gai would've been killed more than a few times if not for Kizuna using THE POWER to project her emotions onto his optical circuits as the Three Sisters. If not for Mamoru and Kizuna, the entire universe would've been doomed, and that's why they were both named in the same part of the theme song.
A relatively minor one: Seeing how the series likes to point out the flaws with its tropes, then make them work anyways, you may wonder why Mikoto's a fairly standard operator pre-Zonuda, but then it hits you: GaiGar, GaiFar, :and Genesic GaiGar don't have keyboards in their cockpits during Fusion, so they need someone on the other end to calibrate the GaoMachines for the current situation, and even if they did, the pilot still wouldn't be able to operate the other GaoMachines from within the Mechanoid until after Fusion (Fusion only allows direct control of the mech they're piloting, and neither Galeon nor PhantomGao have a way to remotely control the other Machines. The pilot can't activate it themself. This begs the question of whether this is standard, or whether it's because the usual pilot's not from the Green Planet. Going by what we see in the first few episodes of FINAL, it's likely that people from the Green Planet can execute Final Fusion without an operator, it's only Guy that can't.
To clarify, I'm saying that GaoGaiGar is one of the few Super Robots that actually requires an operator to direct the component mechas before combining. They're not empathically controlled by the pilot, they actually had to be programmed to do it, and need someone to enter the proper variables and settings for it each time. People from the Green Planet are capable of telepathically doing this (see Repli-Mamoru), while Guy isn't, and thus he needs someone else to do it for him. This is just another aspect of how this series reconstructs the genre, in that it actually gives a viable reason for having an operator instead of "eye candy for the viewers".