I could swear I saw David Tennant in those episode flashes.
There was a flashback of all the old doctors.
Nah the bit at the very end where there was scenes of what's to come, like where he used the gun at the end.
David Tennant? I know which bit you mean, but I must have been looking at the wrong face or something. -scuttles off to doublecheck-
Well look on Youtube and post back with any findings.
I doublechecked, and either I've completely missed it or there is no David Tennant in there. You're welcome to check yourself and prove me wrong, of course. Link