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".
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.
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.
The Aztecs - S1-E6
Other mistake: During the sacrifice scene, the camera bumps into some scenery and suddenly lurches.
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.
Answer: It was never destroyed on-screen; it was intact at the end of the TV movie, and destroyed by the start of the 2005 series. It was destroyed in the novel "The Ancestor Cell," but in a completely different manner to what happened in the series.
DaveJB