Revealing mistake: In episode three, when the root attacks The Daleks in the mining area, the string holding the root up can be seen.
Revealing mistake: During episode three, in the mining area, just before the city's root appears, the tracks on which The Daleks move can be seen.
Answer: TARDISes are generally available for properly authorised use on Gallifrey; they're not usually assigned to a particular Timelord on a long-term basis. The Doctor stole his when he left his homeworld.
Tailkinker ★