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.
Destiny of the Daleks - S17-E1
Revealing mistake: When the Doctor and his companion are running past explosions in the sand, you can see the scrape marks from where the effects team covered up the holes containing the charges. (00:13:00)
The Dalek Invasion of Earth - S2-E2
Factual error: The Doctor states that The Daleks invaded Earth because it is the only planet with a magnetic core. In fact, every planet in the solar system has a magnetic core.
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.").
Earthshock - S19-E6
Factual error: As the spaceship approaches the Earth of 65 million years ago, the Earth looks very much like the present day one. Hasn't anyone heard of "continental drift"? The Earth's land masses of 65 million years ago were not where they are now. (This has been fixed on the DVD)
Invasion of the Dinosaurs - S11-E2
Revealing mistake: At the beginning of episode two, the soldiers firing at the dinosaur are aiming up and well to the left of the creature.
Continuity mistake: When the Doctor and Harry arrive in the cryogenic chamber, they walk around for some time inspecting the chamber and talking. Towards the end, they notice a green slime trail newly appeared on the floor. But the trail was visible in the very first overhead shot of the chamber.
Invasion of the Dinosaurs - S11-E2
Continuity mistake: In episode 2, when the Doctor and Brig arrive at the scene to stun the dinosaur, they leave the stun gun in the jeep. Mike Yates glances down at it and we can see that the sabotage disk is already attached - although he doesn't actually put it on until later.
Resurrection of the Daleks - S21-E4
Audio problem: Davros' lips don't move when he says, "Now for The Daleks," just before he releases the Dalek-killing virus.
Continuity mistake: At many points in this story there are problems with the costume that Zoe is wearing...the zip is often jammed part or all the way open. Not only does this leave most of her back exposed, but the position of the zip tends to change position during scenes, as while off camera Zoe tries to pull the zip back up, only for it to open up again minutes later. (It is a little unkind to say it, but possibly the costume was a little bit too tight for Zoe, causing it 'self unzip'?).
Factual error: Titan is depicted as a Moon-like landscape with no atmosphere. In actual fact, Titan has a nitrogen/argon atmosphere denser than Earth's, and a reddish-orange sky. This was detected almost thirty years before "The Invisible Enemy" was made, so somebody slipped up in doing their research.
Visible crew/equipment: When Leela runs into Toos' quarters (and finds D84 leaning over Toos), we see a low-angle shot of her entering the room. Look at the brief shots of her before and after D84's line, "Please do not throw hands at me," and you'll see the front of the camera that took that low-angle shot jutting out into the doorway behind her, before it slowly retreats out of vision.
The Talons of Weng-Chiang - S14-E6
Revealing mistake: A 1970s newspaper - the headline concerns Denis Healey, Chancellor of the Exchequer in the 1974-79 Labour Government - can be seen in Litefoot's laundry basket in episode three.
Factual error: This story is set in London in 1966 - the Post Office Tower was completed in October 1965). July 12th 1966 was a Saturday, not a Monday.
The Dalek Invasion of Earth - S2-E2
Audio problem: In episode 2 you can hear the Black Dalek clear his throat before speaking.
The Dalek Invasion of Earth - S2-E2
Revealing mistake: When Barbara is throwing her bombs, she grabs the window frame in front of her, which wobbles alarmingly.
Audio problem: When Irongron fires his first gun, the sound is heard before the gun actually fires.
Continuity mistake: At the end of episode one, when the Doctor and Taron spray paint onto the invisible Dalek, they use two different colors. At the start of episode two, the Dalek is suddenly black and painted on all sides.
Factual error: The story is set in 1943. Jean and Phyllis shouldn't readily know who Jane Russell is, as she didn't become famous until her debut film The Outlaw was a box-office hit after the war, three years later. (Although The Outlaw originally had a limited release in the US [but not the UK] in 1943, it was quickly withdrawn by the censors and not released widely until 1946.) True, they could have read about this film in a newspaper or magazine, but considering the strict wartime censorship then in force, it is unlikely.
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