Okay
Spoilers–and a hefty post–follow
[spoiler]Part of this is that no one expected Doctor Number 8, Paul McGann, to make an appearance, as he’d said on twitter he wasn’t in the 50th anniversary. Well, technically, he wasn’t. He was in the prequel minisode! Sly bastard ;)
Anyway, McGann only got a couple of hours of screen time as Doc No. 8 in a pretty bad TV movie in the 90s, about halfway between the mid-80s cancellation of Doctor Who Original and the mid-2000s New Who. In said movie, they dredged up the actor for 7 long enough to have him regenerate into the new pretty boy TV Doctor, but we never did see what happened to No. 8.
All we knew as New Who started is that Eccleston was relatively new at being the Doctor (hey, look at my new ears! he says in the first ep), so No. 9 wasn’t very old, as Doctors go. He later revealed he’d ended the Time War by doing something that destroyed Time Lords and Daleks alike (though portions of both manage to escape and wreak havoc over the years of New Who), but we never see his actual involvement in the war.
It’s always been assumed that No. 8 did the deed and in the process was so injured that he regenerated into No. 9 who was definitely ravaged psychologically by what he’d done. However, at the end of the last season of Who, a “new” Doctor was introduced as some characters literally stepped into the Doctor’s own timestream/personal history to poke around. This one was played by John Hurt, and he seriously broke the chronology that everyone had grown to accept (the series has been pretty overt about poking fun at the numbering of each new Doctor in some way, so their order was fairly well canonized, meaning Hurt’s Doctor couldn’t have come before No. 11 – Matt Smith – or else he’d break the ordering. Yet, if he somehow came after, how was he already in said Doctor’s historical timestream that they were waltzing around in?).
The new minisode opens with a pretty typical play on the Doc’s name as a woman is asking for help and her ship’s AI foolishly suggests a Doctor. Haha, we’re all in on the gig, The Doctor is gonna show up. But which? 10, or 11, who are slated to appear in the 50th Anniversary Special Ep? Maybe Hurt’s Doctor, to teach us a little more about him? Nope!
It was no. 8, who hasn’t been seen on film since his ill-fated movie! He’s older (obviously due to actor’s aging, but the minisode makes no attempt to disguise it, so we are to assume he’s actually older than when last seen in the movie) and mentions some companions that had been written into audio dramas the 8th actor had played in on the radio in England, thus canonizing his fictional history there. He also reveals that the Time War is ongoing and that he’s been avoiding fighting in it–it’s not his war, in essence.
What follows is a crash landing onto a planet where the inhabitants can help him shape the nature of his next regeneration–turns out he was fatally injured in the crash and only has minutes to live in his current (8th) form. Guilted into entering the war before it destroys the whole of reality while he stands back in passivity, he asks them to help him regenerate into a warrior capable of doing the things that must be done to end the war.
He is revealed then to turn into Hurt’s character, who is fully named “The War Doctor” in the minisode. This fits with what we learned at the end of last season–the Doctor doesn’t consider Hurt’s incarnation to be the real thing because he’s the one who chose to not be a healer, a helper. Instead, he was actively formed into a new entity, one capable of great violence.
This repairs the fractured chronology by a technicality. Hurt’s War Doctor might represent the 8th full regeneration of the Time Lord who calls himself the Doctor, but because he’s a “warrior” rather than a “healer,” he doesn’t “count” against the numbering of Doctors. Presumably, then, the 50th Anniv. Special can show us in some form how the War Doctor did his thing before finally regenning into 9–Eccleston–and restoring the more typical numbering scheme. They might not show the actual moment, but at least now fans have a handle on how it all came to be.[/spoiler]
Hope that clears up the various surprises present in the minisode (the reveals of key unexpected actors in unexpected ways and the solution to some timeline troubles that have had fans bickering for months now)