The Creature from the Pit - S17-E3
Revealing mistake: Torvin, stunned by K9, turns before falling, as if looking for somewhere comfortable to land; and the guard who goes to attack K9 and Romana acts very strangely: he stops and curls up before K9's blast hits him, almost as if he knows what is going to happen next.
The Creature from the Pit - S17-E3
Revealing mistake: Before the TARDIS console explodes (as Erato is weaving his shell around the neutron star), Tom Baker casts a sharp look over his right shoulder...no doubt looking to see if the ground was clear where he was due to fall.
The Creature from the Pit - S17-E3
Revealing mistake: Just as the Doctor asks where the TARDIS has materialised, watch the control console wobble. However, isn't it strange that the hat-stand in the TARDIS console room remains upright thoughout...so why does the console wobble, and the hat stand not move in the slightest?
The Creature from the Pit - S17-E3
Plot hole: The Doctor should not need a book on Tibetan as he already knows the language...he went to Tibet in the Season 11 story "Planet of the Spiders." (Of course, that was Jon Pertwee, the 3rd Doctor. Perhaps losing the mastery of the Tibetan language was a result the regeneration into Tom Baker).
The Creature from the Pit - S17-E3
Plot hole: In part 2 it's brought up in conversation several times that all metal is rare on that planet. Handy exposition for the viewers, but it's in fact a really odd thing for the characters to say. The inhabitants aren't giving a tour of their planet (certainly not deliberately at any rate), so why would they state facts that have been well known to them all of their lives? It's a bit like meeting strangers and informing them that two thirds of the Earth are covered by oceans.
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