Board Thread:The Reference Desk/@comment-5545417-20131116122722/@comment-43908-20131124181537

"The Four Doctors" ends with the earlier Doctors in Eight's TARDIS. They display awareness that they will shortly part ways, and only Eight would remember the encounter.

"The Empire of Glass" begins with the Doctor reappearing in his TARDIS after assisting his future selves in "The Three Doctors;" he doesn't remember what happened beyond fading memories of "a dandy and a clown."