Since I don't know anything about QED, I'm not equipped to answer this question. What I can say, however, is that much of what we consider to be "causality" is just a matter of probability. There's nothing in the fundamental laws of physics that says that a flower pot that fell off the window sill and broke into a million pieces an hour ago, can't now suddenly put itself back together and then fly back onto the sill, just as if nothing had ever gone awry. The fact that flower pots don't typically tend to do so, is that this turn of events is
extremely unlikely.
In fact, as far as fundamental physics goes, the forward arrow of time and the backward arrow of time are indistinguishable. I.e., if you were to look at a movie of subatomic particles interacting, you wouldn't be able to tell, if you didn't already know, if the film were being played forwards or being played backwards. (As a slight caveat to this--a caveat that does not detract from what I am saying, but should be mentioned for the sake of completeness--there is one tiny aspect of fundamental particle physics that breaks this time symmetry, but it is a rather subtle one. The physicists who discovered this won a Nobel prize, and as I understand it, why this symmetry should be broken--no matter how subtle the effect--is still a deep mystery.)
What we consider to be the forward arrow of time comes completely from thermodynamics, not from fundamental law. E.g., if the Big Bang occurred at the end of time, rather than the beginning of time, we wouldn't be able to tell the difference, because from our point of view, that would end up being the beginning of time anyway.