I complained a bit when that part about the Dragon Tooth was introduced, mostly over how Chronopolis 's ability to detect temporal stuff. (Back when Chrono'99 first revised the plot, he said that Belthasar would have to rely on historical records.) I think C99 didn't like the Dragon tooth retrieval because it would require another time egg usage.
Yeah, Time Eggs were very rare in the 3 other games and apparently very difficult to make. In CC Lucca never managed to build complete ones, and Belthasar's pink hollow egg may or may not have been complete. On the other hand we use a LOT of Time Eggs in CE.
Another issue is that Sorin
blew up the Dragon Tooth, to prevent the Frozen Flame from using it to recreate Reptites. A destroyed Dragon Tooth can't really be useful as a power source. I guess we could assume that the Chronopolis scientists repair it, but it's not obvious in the dialogue.
Yet another issue, if you go back to the initial point (Chronopolis's need to replace their Dreamstone with another power source), is that it would have been much more simple to simply get the
Sun Stone instead. We could assume that the Sun Stone's radiant signature is incompatible with the Chronopolis cloaking device or something, but again, it's not obvious. The Stone does get a plot point later on in the game though.
So yeah, this Dragon Tooth weak spot is kinda my fault. It's right the middle of the game so I guess it fell under my radar during the plot revisions, compared to earlier and later events.
The following characters gained TTI but weren't accounted for: King Guardia XXI (600s King Guardia), Doan, and optionally, Chrono's mom, Gina. I guess these guys and gal slipped the CE Team's mind when you were writing the story, but if you'd remembered these characters gained TTI, what would you'd have done with them. Also, will we be seeing Norstein Bekkler, Doan, and the rest of the world of the year 2305 in the future?
Eh, you're right. The biggest of these minor issues is King Guardia XXI I think. Gina's lack of TTI can be explained if the party crashed the Epoch on Lavos, and Doan doesn't appear in the game (we were limited by tilesets in the future era).