Revealing mistake: Watch Elena's monitor screen just before she taps some keys and gets the display of information about the XV773 freighter. It's filled with a mass of tiny text which initially looks like just gibberish - but if you look closer, you'll see it's actually the computer program used to create the information display. Someone has even typed in the RUN command at the bottom of the screen, so that all the actress had to do was press the ENTER key and an instant faked "information readout" appears.
Revealing mistake: When Pralix lifts the spanner in the composite shot, bits of debris lift up with the spanner.
Revealing mistake: When K-9 shoots one of the infected men, the blast beam appears to come out of his eyes, then moves down to his snout as the camera moves.
Continuity mistake: In episode four, when the Doctor is patching the communicator into the android's head, he takes off the communicator's top, yet it is back on a few seconds later.
Planet of the Spiders - S11-E5
Revealing mistake: At the very beginning of episode four, the thin pole moving the queen spider can be seen.
The Aztecs - S1-E6
Revealing mistake: In the final fight, Ixta sends Ian staggering into the altar, which slides out of position across the floor. Also, at one point the edge of the raised set they're fighting on is visible briefly.
Revealing mistake: At the very beginning of episode four, after Vince is killed, Reuben's body breathes and his fingers move.
Earthshock - S19-E6
Visible crew/equipment: Just after the Doctor has explained the anti-matter to Adric, the shadow of the boom mike is visible in his blonde hair.
Revealing mistake: At the end of episode five, when James collapses against the wall, it wobbles under his weight.
Visible crew/equipment: When Leela bandages Toos' arm, a member of the crew is visible on the edge of the set.
Revealing mistake: Zadek claims the water door into Castle Gracht is a foot thick. But it is obvious when the Doctor crawls through that it is paper thin.
The Ambassadors of Death - S7-E3
Continuity mistake: Taltalian's French accent mysteriously gives way to an English one in some shots, most notably on location, e.g. when he catches an escaping Liz and says "Get in Miss Shaw".
Factual error: In episode 2, the policemen from 1925 recognise the TARDIS as a police call box, even though TARDIS-style police boxes weren't introduced until four years later, in 1929.
Revealing mistake: The fake snow in episodes one and two is effective - with the exception of when the Doctor is digging up the second Krynoid pod, where it is painfully obvious the snow is styrofoam packing peanuts.
Factual error: In the first close-up view of Mondas, the planet is spinning rapidly so that we can see that its continents are identical to Earth's. But this would mean that Mondas is spinning on its axis once every few seconds - tens of thousand of times faster than Earth. This would be such a fast rotation that the planet would not be able to hold together under the centrifugal force.
The Curse of Peladon: Episode Two - S9-E6
Continuity mistake: As Jo walks along the castle ledge to escape from The Ice Warriors' room, there is, at one point, a quick shot of a piece of the ledge breaking off under Jo's shoe and falling down the cliff face. However, the shoe isn't Jo's. If you look closely, you'll see that the shoe in that brief shot is more pointed and of a darker colour than the shoes Jo is wearing, and has a strap across the ankle instead of being a slip-on.
Deliberate mistake: In episode three, the Doctor and Vira meet a half-changed Noah. He holds a gun on them, then drops it at Vira's feet and the door is suddenly closed. This is because the scene was originally longer and involved Noah begging Vira to kill him before the Doctor shuts the door. It was trimmed down to get it past BBC censors.
Continuity mistake: In "The Ribos Operation", Romana stated that her age was 'nearly 140' (presumably Earth years, although this is never confirmed). However, in the later story "City of Death", Romana says that she is '125 years old'.
Revealing mistake: In episode 1, watch out for the wires pulling K-9 along the beach. (Unlike a real dog, K-9 didn't take well to the soft sandy surface and sank into the sand. Pulling K-9 along on wires provided an illusion of movement when the motor inside wasn't up to the job).
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