My Little Pony: Friendship is Magic - Image #266,731

I don't see the problem Doctor. Its just a loop that will continue forever that it will cause itself.
Ouroboros
Also Rose practically did it. When she wiped out the Dalek emperor she scattered Bad Wolf to tell herself to go to the future, which then creates a loop.

Also I'd like to see you have defeated the weeping angels without the info Sally Sparrow gave you, after you gave it to her via DVD messages.

Doctor who time travel doesn't make sense.
I am so geeky right now.

Dr. Whooves, Doc. Brown would happily Disagree.
The major thing is the fact Past Twilight TOUCHED Future Twilight. That right there is a Paradox.