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.
Earthshock - S19-E6
Revealing mistake: During the "cliffhanger ending" at the end of episode 3, it's blatantly obvious that the three columns of advancing Cybermen are merely mirror images of each other. The head of each column has black head bars indicating leadership, and is holding his gun in exactly the same position.
The Sea Devils: Episode Three - S9-E11
Continuity mistake: The helicopter sent to rescue the Doctor and Jo changes in mid flight. It begins as a grey Sea King marked SO. In the second shot, it has an orange nose and tail stripe and is numbered 56.
The Dalek Invasion of Earth - S2-E2
Visible crew/equipment: Just before Dortman leaves to test out his bomb, he comes towards the camera. When he's doing this, look at the right side of the screen - you can see a crewmember's shadow. It can't be Barbara or Jenny because they then enter from the left.
The Daemons - S8-E5
Plot hole: It is never explained who - or what - killed the man in the churchyard during the first scene (early in part one). It cannot be Bok (the gargoyle) or Azal (the Daemon) as neither of them have awoken.
Factual error: As Jean and Phyllis run into the water to go swimming, they seem to be wearing dark shoes or sandals. But in most of their appearances as Haemovores later in the story, they are wearing bright white (and suspiciously modern-looking) sneakers/trainers.
Answer: In 'The Five Doctors', three separate Cyberleaders are definitely used. So it's likely that Cyberleaders are like unit commanders, of which a fair-sized army might have several.
Daria Sigma