did the little kid imagine the whole thing??
Keiichi's mom is the only who's ignorant towards the whole alien invasion thing? And Keiichi wondering why Gyaos's attack didn't make the news? Yet in a later scene his mom is talking with that alien lady (the evil one). I've seen this movie dozens of times since childhood and always thought Keiichi was either insane (ala Fight Club) or he dreamt the whole thing up by watching too many Gamera movies and Superman.
(I also wish they used the money spent on the space women effects on new Gamera scenes. Ones that don't show him flying around like a Thanksgiving Day parade float)