Okay, some minor spoilers here, people, so be warned: From the recently revealed official synopsis, we know that the modern day sequences of Day of the Doctor take place in 2013. It's also long been known that Kate Stewart is returning, after appearing previously in The Power of Three. But, depending on how things go, this creates a bit of a problem: The Power of Three was set several years in our future, around 2018 or so, and that was when Kate first met the Eleventh Doctor......so how can she meet him now, in '13?
Chances are, Moffat doesn't care; the casual audience that the series is pitched at probably isn't aware of the timespan of series 7A. If questioned, he'd probably say something like, "Oh, it was only fan supposition that the Ponds' final episodes took place in the future." And if fans question it, he would probably say that they can figure out for themselves how it works.