How was she alive in the future??
I hope someone can come up with an answer. This is complicated for me to explain but here it goes: there's a part where Chiaki explains to Makoto that he used his last time leap to save their friend because in the future where he came and where the friend have died, she blamed herself and lived with the guilt (if im not wrong), so that proves that she made it to the future. But now HERE'S THE PROBLEM. She leapt through time to avoid her train accident that morning with the bike. But that was thanks to the walnut that Chiaki brought this time. So the future her shoudnt be alive since this is a exceptional time where she could leap. So the future her shoudnt be alive since she couldn't have avoided it.