Continuity mistake: In this episode part of the TARDIS set was erected incorrectly, resulting in some of the roundels emerging from the wall rather than being indented into it. This is very visible in all the TARDIS 'console room' shots.
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.
Continuity mistake: In episode 4, approximately 5 minutes from the end of the story, Soldeed is shot after he pulls the lever that sets the complex on overload, and then crumples to the ground dead beneath the lever. Then, after the Doctor and everyone else get out of the complex, we see a selection of shots taken inside the complex - one of which is the room with the lever that Soldeed pulled, except he's no longer there...
Continuity mistake: After Skagra demands the book from Professor Chronotis, as Skagra's sphere floats toward Chronotis he's wearing his eyeglasses, but then the Professor's eyeglasses vanish and reappear while his hands are raised.
Continuity mistake: During the animated portions of Shada's missing scenes, in numerous shots an illustrated character's clothing (buttons, scarf, etc) become flipped, sometimes even within the same shot. Example: when The Doctor goes to the physics lab and meets Clare Keightley, note her buttons and The Doctor's scarf.
Visible crew/equipment: After Chris exits the TARDIS with the medical kit, Romana places the collar around the Professor's neck. When Romana tells Chris that Chronotis, "Should be able to think with it," in the next closeup of Chris the moving boom mic is visible at the top of the screen, before he kneels down.
Plot hole: The Doctor and Romana comment on a recording which has finished playing before they have entered the room. Not only that, but all the other characters behave as if the Doctor and Romana had seen this recording.
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).
Continuity mistake: In "The Deadly Assassin" the Doctor's blood is red but in "State of Decay" his blood is suddenly dark blue. Then it's back to being red in "The Two Doctors."
Revealing mistake: The Grove is one of the most obvious indoor sets masquerading as a lush outdoor environment. The sound the actors' feet make on the floor is especially unforgivable.
Revealing mistake: When the Keeper is on the TARDIS, he asks to borrow the screen. But on the upper left corner, you can see it over where it's meant to be.
Continuity mistake: The Doctor somehow manages to secure his scarf across the catwalk, despite having only gone on seconds before the Master. He then manages to put it on again during the seconds it takes for the Master to alter the angle.
Castrovalva - S19-E1
Continuity mistake: The Doctor's shoes are different at the beginning of this story compared to the ones at the end of the last story.
Castrovalva - S19-E1
Deliberate mistake: The newly regenerated Fifth Doctor is wearing completely different shoes than the Fourth Doctor did in the previous story. This is deliberate. The boots worn by the Fourth Doctor were actually privately owned by actor Tom Baker. Still, a mistake but this is why.
Factual error: There are currently well over 700 different native Australian languages, and undoubtedly many more have been extinct for centuries. The chances of a 20th Century European-Australian such as Tegan being able to understand a native Australian language from around 35,000 years ago are so astronomical it is beyond belief.
Visible crew/equipment: In episode 1, when Monarch tries to open the TARDIS, you can see the head of a crewmember hiding behind a crate in the foreground.
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.
Earthshock - S19-E6
Visible crew/equipment: As Lieutenant Scott is moving up the scaffold staircase, you can see someone at the top of the screen reading a script. (01:04:20)
Earthshock - S19-E6
Revealing mistake: When the Cybermen break through to the bridge, they brush against the door and it bends as if made of cardboard. It was supposed to be made of reinforced steel. (01:09:10)
Earthshock - S19-E6
Continuity mistake: The hole that the Cybermen make in the door increases in size just before they step through it. (01:09:10)
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