Theory:Doctor Who prose discontinuity and plot holes/The Eight Doctors


 * When the Eighth Doctor travels to his Fifth incarnation's timestream Tegan asks if he was the Doctor caught in the Time Vortex(in The Five Doctors). However, Tegan actually met the Fourth Doctor first, and was there to watch him regenerate into the Fifth Doctor(in Logopolis).
 * Tegan is surprised at the Eighth Doctor's appearance and so is talking before thinking.
 * Alternatively, since she's in the middle of one of the messiest Doctor Who stories ever written, she could have been so discombobulated by the execrable nonsense around her that she had no idea who was who anymore.