User blog comment:New Dalek Paradigm/Why I didn't like The Day of the Doctor/@comment-5052737-20131124200752

Doctor Who TV said this about the "Doctors Assemble" scene:

"The biggest piece of timey-wimey ball occurs at the climax when the Doctors come up with possibly the cleverest plan of their entire lives. The Doctors start the calculations needed to save Gallifrey at the First incarnation, which shouldn’t be possible. This trick is actually borrowed from the Destiny of the Doctor audio series. In it, the Eleventh Doctor communicates with his past selves, allowing them to see what one of their future incarnations will look like, but by the time of The Eleventh Hour, the Doctor still doesn’t recognize himself, despite having seen himself nine times over. Evidently, any knowledge from contact involving future incarnations that are not the same incarnation is wiped clean from a Time Lord’s memory until the current incarnation’s adventure takes place. The same thing happens here. The First Doctor must’ve been told of the Time War by his far future at some point in his life and started the calculations in his TARDIS. After which, he forgot about the foreknowledge. But these calculations continued to run up until they reached the Eleventh Doctor’s TARDIS. All the Doctors presumably learned of the Time War just long enough to play their part in saving it before the knowledge was deleted from their memories and history was set back on track."