Revealing mistake: The shot of the two motorbikes colliding with each other and exploding into flames is very unconvincing. Watch carefully, and you can "see the join" where a shot of the two motorbikes passing each other (and NOT colliding) is replaced by a "staged" fiery explosion.
Continuity mistake: In episode 2 of "Survival", Midge is captured, and the sabre tooth he's carrying gets knocked to the ground. Neither he nor the Master pick it up before they teleport to Earth. Yet in Episode 3, the Master is able to present the sabre tooth to Midge as he's about to ride his motorbike towards the Doctor.
Continuity mistake: At the beginning of episode 3 when the Doctor tells Ace that she can do what the Cheetah People can, he puts his hand on her shoulder. In the next shot his hand is no longer there, but it's back again in the next.
Continuity mistake: When Karra dies and turns back into her human/humanoid form she is wearing a black top that they did not wear as a Cheetah Person.
Continuity mistake: When the Doctor picks up the humanoid skull his hat is looking normal but in the next shot the brim of his hat is folded down and completely flat. In the next shot it's back to not folded again.
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 ★