The Source of the Mysterious Ticking

I know that it's unlikely that many people will ever see this, but it's been bugging me for a while now.
In the episode, The Girl in the Fireplace of Doctor Who, The Doctor realizes that there is a Clockwork Robot in Reinette's room because the clock is broken, but he can still hear ticking.
However, to get into the room, the Doctor spins the entire Mantelpiece around. Thus, the intact clock we see when he first approaches the fireplace should now be facing into the room.
And, because I'm operating off memory here, If the clock that The Doctor sees on board the spaceship is already smashed, well, how did it get to be like that? The only way it could have done so is if the robot smashed the one on its side, before crawling through the fire. and I know those robots weren't that smart, but they can't have been that dumb.
So, to the writers I say;
I know that sometimes continuity between episodes or seasons (Still trying to figure out how River got that blue sonic) is hard to keep, but in the one episode? Think, people!