Revealing mistake: In episode four, the camera wobbles when the Doctor brings the gun to Stael.
Other mistake: Several shots are repeated during the implosion of the priory.
Continuity mistake: The TARDIS is missing its light the first time it's seen.
Continuity mistake: In the opening TARDIS scene, after the TARDIS lurches from the time scanner, the Doctor's hat rack can be seen standing upright. Then Leela picks it up in the next scene.
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 ★