9. Season 6B
For the second one in the list I'm going to go with the classic season 6B theory on the off chance that there's five people out there who haven't heard of it. I thought it was an interesting time to bring it up as it is a similar idea to the War Doctor having adventures that we hadn't seen on screen and of course, we just saw a much older Tom Baker appear on screen too. So the basic theory is that the second Doctor and Jamie both appeared in The Two Doctors alongside the sixth Doctor but the earlier incarnation and his companion both looked substantially older than they did at the end of The War Games. Obviously in the real world we can't avoid aging, but usually the Who writers think of some clever way to explain why their far-back characters look wrinklier and slower. However, this time this wasn't explained on screen at all. Not even a throwaway line. So the thought is that the Doctor and Jamie continued to have adventures before the Time Lords summoned the Doctor at the end of the War Games and sent Jamie back to Scotland. We're so far beyond that point that we're likely never to have any proper answer to this one as I doubt anything now will reference it.