Hmmm. . . interesting question. I honestly had never considered it before, and although the alien theory is a little bit of a stretch, FF8 does seem to have a lot of technology which comes from past civizations whos methods of building have been forgotten.

For example, the GARDENs used to be "shelters" of some kind, hence their ability to transform using "ancient machinary." However, although Cid and Edea had the Shumi help fund the plans to build renovate these shelters into GARDENs, Cid seemingly had no idea how the machinery transformed the GARDEN. He seemed genuinely shocked when it transformed and took off. In fact, he mentions the machinery which might help them escape as if it were a rumor. Strange, considering he was the one who founded the place. Even stranger is the knowlege of the Fisherman's Horizon people, who know exactly how to fix the GARDEN and even mentioned that they helped build it in the first place, and yet the offer no further explanation. It's almost humerous, like, "Oh, would you look at that. That giant flying structure that just crashed into our town looks like something our ancestors built a long time ago. Whaddya know." What were these structures sheltering people from? The lunar cry? How come the flying technology which propels these vehicles wasn't applied to other modes of transportation? Was if because FH is isolationist and the technology never spread?

Also, the Lunatic Pandora was an excavation site. The Estharians (was it them? i'm not sure. . .) found it buried and dug it up, like Tut's Tomb or something. So its difficult to say if it was orginally from space, or an artifact from an ancient civilzation. It's also attached to the Lunar Cry. . . interesting.

Finally, there's Centra Ruins. Apparently, Centra was quite an advanced civilzation before it was destroyed by the Lunar Cry. Did the people of Centra create the Lunatic Pandora not realizing the Cry that would result and destroy their city? Did they then "abandon ship" so to speak in the "shelters" which have now become GARDENs? Then, the Lunatic Pandora was left to be buried until it was uncovered by archeologists studying the Centra Ruins? If so, where did the orginal inhabitants go? Shumi Village?

So maybe it is aliens, or maybe the technology is like that of the legendary Atlantis - an advanced civilzation which was destroyed and then forgotten. Although, Atlantians are also often connected to aliens as well. Well, that was rambling, but hopefully it sparks ideas in others. I'm interesed to hear what you guys have to say.