The Monster of Peladon - S11-E4
Plot hole: The temperature of the air being blown into the mines is controlled from the communications room when the Doctor needs to knock out The Ice Warriors. But conveniently, the ventilation system is controlled from the refinery when Eckersley needs to suffocate the miners.
The Daemons - S8-E5
Continuity mistake: In part one, watch for the continuity error when Miss Hawthorne turns to face the policeman: her cape appears and disappears from around her shoulders from shot to shot.
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.
Revealing mistake: In episode 5, Codal discovers that what he thought was Taron is an invisible Spiridon. However, there is a glimpse of the actor inside the fur costume as he attacks Codal.
Visible crew/equipment: In episode five, when Taron knocks out the Spiridon, you can see a BBC camera in the foliage behind him.
Continuity mistake: In the very first scene of the story, Jo is holding a gun as she opens the TARDIS doors, but when they come into the console room, she has no gun and is using both hands to support the Doctor.
Visible crew/equipment: In episode three, when the Doctor enters the Pavilion of the Summer Winds and shuts the door, the door slowly swings open again. A hand then appears from behind the set wall and pulls the door closed.
Continuity mistake: In episode 3, after the Nitro-9 explosion which Ace uses to blow up the wall, sealing up the mine shaft, the wall is can be seen still standing, unaffected by the blast. However, after a quick cutaway to the Doctor and Ace, the wall has vanished completely by the next shot.
Audio problem: The music accompanying the closing credits fades down part way through (at a different point in each of the four episodes) and simultaneously fades up at a different point, the net result being a rather disjointed-sounding edit.
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: The calendar which shows the date to be Monday, 2nd March, 2472, is two days out. 2nd March 2472 will be a Wednesday. And who made the calendar if the colonists left Earth over a year earlier?
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.
Audio problem: When the Doctor chops a brick in half, you can tell that the brick is really made from balsa wood by listening to the sound it makes when it hits the ground.
Plot hole: In episode 4 of "The Curse of Fenric", the weather is supposed to change for the worse and become very stormy. The Doctor and Ace are seen to be sheltering under an umbrella from the torrential downpour. Yet the skies in the background are bright, blue and sunny...
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.
Revealing mistake: When the Doctor confronts D84, the robot is shown in profile as the Doctor forces it to speak. The movement of the actor's jaw is visible behind the mask.
Revealing mistake: In episode 3, the section of wall K-9 knocks down is obviously precut, complete with debris on the floor.
Continuity mistake: When the Doctor and Ian encounter the Frankenstein monster in episode four, you can see a Dalek behind them, even though it's long before The Daleks arrive in this time zone.
Plot hole: Professor Jones says they tried to borrow the cutting equipment a few weeks ago, but Mr. Stevens says it was yesterday. One of them must be wrong...
Earthshock - S19-E6
Continuity mistake: The mouth panel of the Cybermen costumes was originally intended to be a clear perspex panel. During filming, it was felt that this showed too much of the actor inside the Cyberman costumes. So a decision was taking - mid way though filming - to paint over the 'clear' panel with silver paint. However, this does result in the mouth panels of every Cyberman alternating from 'clear' to 'silver' from shot to shot.
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