Marco Polo - S1-E4
Other mistake: In episode seven, Kublai Khan refers to backgammon as a game of cards....obviously he's not an experienced backgammon player.
Other mistake: William has a bit of a nightmare, completely throwing the others during one scene by saying the same line ("It's not very likely") twice, and fumbling the line "You knocked both Susan and I unconscious". He also omits the scripted explanation for the melted clocks.
Invasion of the Dinosaurs - S11-E2
Other mistake: The Tyrannosaurus rex which appears in this story does not actually roar; instead it says the word 'roar' several times. There may be little scientific evidence as to what sound a T. Rex made, but it is unlikely that any of them spoke fluent English.
Other mistake: When the Doctor pulls Zoe and Jamie back into the TARDIS, look at the scanner screen. It has the words 'Producer Peter Bryant' written on it.
The Dalek Invasion of Earth - S2-E2
Other mistake: Ian has completely forgotten the distinctive shape of a Dalek. It's only when the Dalek starts speaking that Ian says to the Doctor, "that voice". Yet later when they are at the saucer, he talks to the Doctor about the new back of the Dalek having a disk on them now.
Other mistake: The Master says he wrote 5,000 words a week for 25 years and Zoe says "but that's over half a million words." Yes it is, to be exact, six and a half million words. (5,000 x 52 x 25 = 6,500,000).
Other mistake: The Cyber Leader is supposed to follow the Master's footsteps exactly in order to get across the chessboard. He doesn't. This cannot be classed as a character mistake because the Cyber Leader knew what was involved. I believe this mistake was caused by the actor not being able to see the chessboard through his helmet.
Other mistake: When Marius injects the cloned Doctor and Leela into the real Doctor, the syringe is full of air, although the later graphic shows them in liquid.
Earthshock - S19-E6
Other mistake: In episode 4, as the Doctor, Tegan and Nyssa are being led away from the bridge, the Cyberleader loses his footing when he gets to the bottom step, and stumbles/trips up (He recovers himself very quickly; so quickly in fact, that this mistake was left in the finished episode). (01:24:45)
Other mistake: After Linx plants his flag in the ground claiming Earth, Irongron and Bloodaxe look offscreen for no reason, as though the shot is finished.
Other mistake: The power output in the Doctor's shed reads "Megga Volts" instead of "megavolts."
Other mistake: In episode two, when Poul enters the room where Uvanov and D84 are holding Leela, the body of Cass breathes.
Other mistake: The end titles of episodes 2, 5, and 6 of "The Green Death" were run backwards and upside-down. According to some published accounts, this was due to the telecine operator forgetting to rewind the end title film sequence before playback.
Other mistake: Several shots are repeated during the implosion of the priory.
Other mistake: In episode one, when the crew wonders what The Sensorites will do them, the camera zooms in on the Doctor as he says, "or kill us?". It then jerks with an audible click as though hitting something.
Resurrection of the Daleks - S21-E4
Other mistake: When the Doctor's mind is scanned, we see his previous incarnations and companions, but Leela is not shown. Katarina is represented by a black and white photograph.
Other mistake: When the K1 Robot breaks out of Kettlewells factory in part 2 or 3, it trips up.
Other mistake: What happens to Tegan's bag when the plague victim transforms into the cavalier? It doesn't appear to be left behind, even when the cavalier later vanishes.
Other mistake: In episode 3, watch the scene where the co-pilot is shooting; you can see his pants rip straight down the seam at the back - which unfortunately happens to be the part of him facing the camera at the time. He then wanders around for most of the rest of the episode with the tear in his pants plainly visible.
The Daemons - S8-E5
Other mistake: When the Master is in the cavern, he lights the candles with a taper, then shakes out the taper which snaps in half.
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