So I read the Void Trilogy by Peter Hamilton a few weeks ago, and one of the subplots went like this: in a world of psychics, one young man has exceptionally powerful abilities. Throughout the books, he learns of increasingly incredible things he can do, until he realizes that he can turn back time itself. Specifically, he can think about any moment in his past that he can remember clearly, and rewind the universe back to that moment (but with all his memories intact). This is where things get a little bit nuts.
For the rest of the book, he tries to make everything right with the world, because he's that sort of character. It takes a terrible toll on his mind at times, but in the end, he lives a life such that there's nothing he wants to go back and fix, and he has reached fulfillment. Happy ending, right? And then he goes and, on his deathbed, gives the secret of turning back time to everybody else in his city - and this is where my brain implodes in dismay.
If zero people know how to turn back time, then things make sense, and history proceeds in a boring linear fashion. If one person knows how to turn back time, then things are still simple enough to wrap your head around, because you can trace a single thread of narrative throughout whatever they do - by designating them the "main character" in the story, the story makes sense. But if two or more people know the secret, then things get Terribly Complicated.
Here's one trivial example of how screwed up the universe would become: imagine a game of Rock-Paper-Scissors between two especially competitive people that know how to turn back time (Rewinders?). The entire universe would be locked in a loop until one of them got bored.
There are weird issues surrounding seniority. If two Rewinders are going back and forth on something, the winner is going to be the one that can go the farthest back - back to before the other one existed, perhaps. If we follow this train of thought, then the winner in any conflict is going to be whoever is the oldest.
On the flip side, there are weird edge cases around death. If I sneak up on someone and kill them before they can react, then that's it for them, I've won, no second chances. This is the only way I can see to break out of a loop without first going through the infinite regression tango, and giving the victory to the older person. A world full of Rewinders would have a lot of immortals trying to kill each other, really - sort of like The Highlander but with more mindfuck.
I'm not really going anywhere with this post. Honestly, I just thought it'd be fun to actually think through some of the consequences of a world with Rewinders. :D