Continuity mistake: The Doctor's scarf vanishes while he's detained in the crew's quarters.
Continuity mistake: From time to time in episode four, the "frozen" robots on the command deck can be seen to wobble - the most noticeable is when SV7 is threatening Uvanov over the communicator.
Continuity mistake: In episode four, when the Doctor is patching the communicator into the android's head, he takes off the communicator's top, yet it is back on a few seconds later.
Continuity mistake: When Toos is being hunted by a robot, she shuts the door on its hand. When you see this scene from the inside of the room, the robot's hand is trapped at a different place to the next shot, which is from outside the room.
Continuity mistake: When Uvanov captures Leela he says she has killed three people, but he only knows Chub and Cass are dead. Then Poul tells him about Kerril.
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 ★