Continuity mistake: In Episode 1, the TARDIS crew pass out from the change in pressure as they descend into the Earth. However, at the end of episode four, they climb out on foot and suffer no ill effects.
The Moonbase - S4-E6
Audio problem: If you listen carefully to the soundtrack of part four of "The Moonbase", some 'chatter' and 'feedback' from the floor manager's headphones can be heard. (At the time this particular episode was recorded, there was just a one-week gap between recording Doctor Who and transmission, so there was no time available to re-record the episode, and this mistake had to be left in).
The Moonbase - S4-E6
Revealing mistake: The doors and walls wobble badly as Jamie and Ben barricade the entrance to the medical unit.
The Moonbase - S4-E6
Audio problem: In part 4, when the Cybermen are outside The Moonbase controlling the workers, the mouth of the radio operator does not move when he is speaking to them. Furthermore, a few of the Cybermen's mouths outside The Moonbase are stuck open when they have no dialogue.
Deliberate mistake: The character of "Chicki" is played by a completely different actress in episode 4 to the one who played her in episode 1.
Visible crew/equipment: Near the end of episode 3 the inspector is on the plane and just before he goes to look for Captain Blade the camera zooms out and the top of the set is visible.
The Evil of the Daleks - S4-E9
Visible crew/equipment: When the Doctor and Jamie enter the secret room watch the top left corner. A boom mike shadow appears and then moves out of shot.
The Evil of the Daleks - S4-E9
Continuity mistake: (Animated version). Waterfield puts down the photo of the Doctor on his desk but the next time we see his desk the photo is no longer there and then later it's back on the desk again, without Waterfield having moved it.
The Tomb of the Cybermen - S5-E1
Revealing mistake: When Kaftan is activating the revitaliser controls, you can see Patrick Troughton moving into position for when he runs and grabs her.
The Tomb of the Cybermen - S5-E1
Revealing mistake: The Cybermen retreat into their tombs backwards; this was achieved by simply having the film of them coming out of their tombs run in reverse.
The Tomb of the Cybermen - S5-E1
Revealing mistake: When Jamie and the Doctor try to open the doors to the tomb, watch them push it with their feet.
The Tomb of the Cybermen - S5-E1
Factual error: When the group divide up into parties, the leader says they need to be at the rocket at 1630, so meet here at 1625. He then goes on to say that will give them an hour to look for anyone that's missing. The other actors seem to notice his mistake because they either look puzzled or look off camera, probably seeing if anyone would shout "Cut."
The Tomb of the Cybermen - S5-E1
Revealing mistake: During the fight scene between Toberman and the Cybercontroller, the Cybercontroller uses a very visible harness to lift Toberman over his head, and the wires attached to the harness Toberman is wearing are also very visible. When Toberman, in return, lifts the Cybercontroller above HIS head, it is obvious that what Toberman is lifting is an empty costume, with no-one inside it.
Continuity mistake: At the start of the story (the beginning of episode 1) the TARDIS materialises on its side, but at the end of the story (the end of episode 6) the TARDIS dematerialises right side up.
Plot hole: We twice see a map of how far the ice is away from the house, once in the first episode, and later in episode five. The ice has moved most of the way across the map in this time, and the distance it has moved is stated to be a 100 metres. This would place it only 20 metres from the base. The problem with the distance is that it takes Penley quite a while to get the injured Jamie to the base, including a stretch across open ground. Also, The Ice Warriors weapon targeter suggests the base is as much as two kilometres away. So just how far away is the ice; 20 metres, 2 kilometers...or somewhere in between?
Factual error: The Doctor postulates that ammonium sulphide will poison The Ice Warriors because the Martian atmosphere is composed mainly of nitrogen. However, it is the EARTH's atmosphere that is mainly nitrogen (78%) whereas Mars' atmosphere is 95.3% carbon dioxide.
Factual error: It is stated that removing all the plants caused carbon dioxide levels to drop. But plants absorb carbon dioxide, so removing them would create an increase.
The Enemy of the World - S5-E4
Audio problem: In episode 3 of this story it is noticeable that practically every sound in this episode has been re-dubbed and as a result is out of synch - sometimes quite badly. An example is when Milton Johns has his thugs break into Giles Kent's trailer - there's a three-second lag between the breaking of the plates and the sounds they make. (This may be simply due to the only surviving copies in the BBC Archives being these "badly dubbed" ones, recovered from obscure sources).
Factual error: It is claimed that a meteor shower has been diverted towards the Wheel by a star in M13 (the Hercules Cluster) going nova. As M13 is a globular cluster in the galactic halo, some 34,000 light years away from Earth, it would have to be one almighty nova to affect the course of a meteor shower in our solar system - due to the countless gravitational forces between M13 and the plane of the Milky Way - and been caused at least 34,000 years before the time of the story.
Character mistake: The Doctor (Patrick Troughton) makes one of the funniest fluffed lines in the entire history of Doctor Who in the final episode. With all sincerity he says "We'll all be dead soon, unless you switch over to the sexual air supply." (The word Troughton was probably looking for was "sectional.").
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