Fridge Horror: In Gamera vs. Guiron, Gamera flies to an alien planet and battles the knife-headed Guiron, eventually killing the beast. But think about it... This was Guiron's home planet. And he was fighting off an alien invader. No different from what monsters like Gamera and Godzilla do for Earth. Gamera killed another planet's Gamera.
Um, seeing as at that point in the movie the planets only other inhabitants were two Brain-Eating Space Babes, who get their comeuppance at the end, I wouldn't feel too bad about that.
The Heisei trilogy contains examples of:
Fridge Brilliance: See early season weirdness first, Kaneko was touching upon the three major monster creations! 1st: created by man/ancient precursors (Godzilla, Kamacarus) , 2nd: nature/alien/evolution (King Ghidorah, Baragon) , 3rd: mythology (Mothra, Barugon, King Ceasar).
Also Osako changing jobs each film may in fact be a brilliant reference to actor Kojiro Hongo who played several main male leaders in several Showa films. From a photographer, pilot/opal thief, construction worker, boy scout leader. Albeit they were not the same character from film to film.
Having re-watched Gamera 3 and then watching the original Gamera (MST 3 Ked) there might be some fridge brilliance in the set up of the very first movie and the finale of the trilogy. Gamera 1 has a designated kid hero who is saved by Gamera and thus apparently being a Friend to All Children allows the giant turtle to have some kind of moral high ground and can get away with torching Tokyo with all adults being wrong in wishing Gamera harm. Gamera 3 has the giant turtle possibly totally accidentally saving a child while killing about 20,000 people all to kill two Hyper Gyaos. The only difference in the two situations, morally, is that the Heisei Gamera at least had the benefit of saving the Earth in two previous movies and the Showa Gamera's first heroic act was saving Toshio. A disturbing call back not just Guardian of the Universe but to the very first movie.