http://www.rpgamer.com/news/Q3-2005/090105b.html
According to this 2005 article on RPGGamer, which I'm sure many people here are familiar with, DoC, BC, and CC were all planned simultaneously, although developed by different teams. Maybe this article has been debunked since then, I don't know, but if it's still taken to be credible, then that means shout-outs to DC were deliberately planted in BC in an uncharacteristic attempt by Square to ensure some kind of continuity.
I agree that, at first glance, the Junon Cannon is not well-placed strategically to act as a deterrent against Wutai, but then again, the whole game doesn't hinge on the Junon Cannon being in a sensible place. Moreover, when the Junon Cannon became the Sister Ray and was fired at the Northern Crater, the mako missile sucessfully covered a distance not much less than the distance (as the crow flies) between Junon and Wutai, without hitting anything else in the way except for poor Diamond Weapon, and negotiating its way around some mountain to boot - so maybe the Junon Cannon wasn't in such a silly spot after all? Maybe it was smart to locate such a powerful weapon of mass destruction right in the heart of the Shinra Empire, where it could be more easily defended.
Maybe the Wutai War started over ShinRa's determination to build a reactor, but then became a matter of (Presidential) pride, and maybe by the end of the war Wutai's economy was so devastated that building a reactor there was no longer economically viable?
Giant scorpion robots aren't very hard for
Zack to destroy. Cloud and Barret had some trouble with it (at least, in my game they did). If, instead of Cloud and Barret, it had been Biggs and Wedge who'd set the bomb, the Scorpion would have made mincemeat of them.
Everyone's entitled to their own headcanon. I just find the whole idea of Deepground so utterly improbable that I just can't be doing with it. Like I said, logistically it's completely impossible. And anyway, why would the President want to keep this terrible army a secret? He didn't keep SOLDIER a secret; they were the poster boys for his company. The only thing they kept secret was the way the SOLDIERs were made.
And what use is a deterrent if nobody knows you have it? At least that big-ass cannon was intimidating, even if it was for nothing but show. That was the Old President's way: panem et circenses. Plus, I ask again, what possible enemy could there have been anywhere on the planet that could have justified going to the trouble and expense of creating Deepground - and then keeping Deepground hidden on the off-chance that this hypothetical and totally non-existent enemy attacked? Wutai was a spent force. Avalanche was just a bunch of terrorists - and according to the timeline, the President founded Deepground
before Avalanche became active.
Like I said before, canonically President Shinra has no pet projects that don't relate in some way to the Promised Land/the Cetra. If he did have another project, surely it would be an attempt to discover the fountain of youth, or perhaps breed the goose that laid the golden egg. Why does he need Deepground, when he has Sephiroth?
Deepground is nonsensical. I feel that Vincent should have pointed this out.