Plot hole: In episode 4, watch what Romana does to Professor Kerensky's time machine in order to make it work. It is surprising that the time machine works at all, considering she is supposed to be in Paris at the time. Romana wires up the time machine to a British (i.e. 3-pin 240 volts) electric plug instead of a "continental" 3-pin 110 volt plug.
Plot hole: The sketch of Romana is different when it's seen outside the café from the one seen inside the café (and just who's doing the sketch, and why?).
Revealing mistake: In episode 2, when Scaroth locks the Doctor, Romana and Duggan in the basement dungeon, and Duggan lights the lamp, notice that Tom Baker is standing between that lamp and the actual stage light used to brighten the scene. So, as the lamp is lit in front of him, Tom Baker's BACK (and not his front) glows bright under the increased illumination.
Continuity mistake: When the Count's henchmen come into the café to get the Doctor, Romana and Duggan, they usher them all out at gunpoint. When you see them in the location filming in Paris, Duggan's not there...but back at the Count's place (in the studio in London) he's reappeared.
Revealing mistake: In episode one, Scaroth's 'Jagaroth skin' on his wrist flaps about. Either that's a badly fitting piece of costume...or he's suffering from severely peeling skin.
Plot hole: The Atlantic Ocean didn't exist in Early Devonian times (c.400 million years ago), so Scaroth's ship could not have been where the Doctor claimed. The Atlantic was formed when Europe and Africa separated from North America around 160 million years ago and is still growing. What is now the sea-bed was once covered up by several miles of Continental Shelf. The Early Devonian landscape would have been far from barren as plantlife was well established by then. So, either the Doctor's theory that Scaroth's exploding ship caused the creation of life on Earth is wrong, or it was much earlier than he said.
Continuity mistake: In "The Ribos Operation", Romana stated that her age was 'nearly 140' (presumably Earth years, although this is never confirmed). However, in the later story "City of Death", Romana says that she is '125 years old'.
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.
Plot hole: When the Doctor goes into the CET projection of Eden, to fight the Mandrells, he disappears into the bushes on the left-hand side of the screen. Cue much shaking of foliage, and Tom Baker's cries of 'ooh', 'aargh' and 'ouch'. The Doctor then reappears with his clothes all tattered and torn, due to his 'fight' with the Mandrells...but the the fact that there is not a mark (not even a scratch) on Tom Baker is something of a giveaway that all Tom Baker did was disappear behind some bushes and do a quick change into a tattered version of his costume.
Visible crew/equipment: In episode 2, as K-9 seals the wall panel, watch out for the hand which emerges to hold it in place.
Revealing mistake: Watch the Mandrells closely, especially in the later parts of the story: one of them seems, at one point, to have forgotten to zip up the back of his costume.
Revealing mistake: In the very first shots of this Doctor Who story, it is obvious that the "Empress" Spaceliner is a model - you can even see the stick that holds the model in place.
Plot hole: When Della gets shot in the face in episode four, she clutches her stomach. (What is even more remarkable about this error is that this keeps happening over and over again: someone gets shot and falls to the ground, clutching their stomachs, regardless of where they have actually been shot. See the error in Season 14's 'The Deadly Assassin' for an example of the SAME error occurring).
Revealing mistake: Geoffrey Hinsliff (playing Fisk) accidentally refers to Tryst as "Fisk" at one point.
Continuity mistake: When the Doctor finds the vraxoin vial in episode 1, he puts it in his right coat pocket, from where it is then removed by Stott. However, at the end of episode 2, Costa's scanner finds vraxoin traces in the Doctor's LEFT coat pocket.
Continuity mistake: In this episode part of the TARDIS set was erected incorrectly, resulting in some of the roundels emerging from the wall rather than being indented into it. This is very visible in all the TARDIS 'console room' shots.
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