First off, sorry if this has been mentioned before.
I've heard rumors that FFX is tied in with FFVII. Something about X being a sequel to VII or whatnot. It kind of made sense to me when the character aptly named "Shinra" in X-2 was speaking of a way to draw energy from the planet. ::cough:: Mako ::cough:: But, I was actually surprised about the somewhat subtle references to X throught Dirge of Cerberus.
Shalua. The first thing I thought when I saw her was Auron. Her arm was hanging out of one sleeve and one of her eyes was closed shut. The physical resemblance was uncanny. Not that her personality matched his, but the exterior qualities were just eerie.
Nero. He reminded me of Anima so much. The arms crossed over each other and his face being wrapped in bandages, or whatever it is his face is covered in. Plus, him making people disappear with the darkness made me think of Anima blinking people out of existance.
Now, those two I doubt have an actual connection between the two games. I just thought that they were both interesting. The one other thing I noticed, however, does seem like it would connect VII and X.
When you are on the Shera, you can speak to different crew members. One of the crew members tells you that the Shera was actually some old technology that they salvaged. This technology doesn't run on Mako, but some unknown source. Automatically, I thought about the airships in FFX. I haven't played that game in a while, but I know that the airships in that game did not run off of Mako. So, maybe the airship was some pre-catastrophic machine (or machina, in this case) that was present during X era.
These are all things that I have been think about, as of late. Anybody have anything they would like to comment on or add?