Marco Polo - S1-E4
Other mistake: In episode seven, Kublai Khan refers to backgammon as a game of cards....obviously he's not an experienced backgammon player.
Other mistake: William has a bit of a nightmare, completely throwing the others during one scene by saying the same line ("It's not very likely") twice, and fumbling the line "You knocked both Susan and I unconscious". He also omits the scripted explanation for the melted clocks.
Other mistake: In episode one, when the crew wonders what The Sensorites will do to them, the camera zooms in on the Doctor as he says, "or kill us?" It then jerks with an audible click as though hitting something.
The Daleks - S1-E2
Other mistake: Why does The Daleks' prison have beds? The Daleks don't need them and clearly state that they have no idea what the Thals look like, speculating that they are "horribly mutated".
The Aztecs - S1-E6
Other mistake: During the sacrifice scene, the camera bumps into some scenery and suddenly lurches.
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 ★