The Doctor's final monologue was recorded in post-production when it was clear that Doctor Who was cancelled.
It had been decided that, for the struggle between The Doctor and The Master, Sylvester McCoy would not wear the cat-like contact lenses made for those "infected" by the planet, although a pair had been fashioned for him. At the last minute, though, McCoy elected to wear them anyhow.
The Doctor's closing monologue was added by Andrew Cartmel when it was known that the series was cancelled.
Ace's fate was never revealed after "Survival" and the 30th anniversary special Doctor Who: Dimensions in Time (1993), yet her character is alluded to in Death of the Doctor: Part One (2010); as a woman named Dorothy (Ace's real name) was the founder of a successful charity known as "A Charitable Earth", (the acronym of which was "ACE").
The abandoned 27th series, which was to had been broadcast in 1990, would had seen Ace leave and The Doctor gaining a new companion in the form of cat-burglar Raine Creevy.