Visible crew/equipment: Part 4, A Race Against Death: After the Doctor states he's going off on an expedition, John still struggles to warn the Doctor, and when the Doctor tells Carol, "Now you stay with him, I think he's getting better," a boom mic becomes visible at the top left side of the screen.
Visible crew/equipment: Part 3, Hidden Danger: When the First Elder tells the Doctor, Ian, and Susan about their refined aqueduct water beneath the city, Ian drinks some of it. Then just after the Doctor says, "Vintage water," the tip of the boom mic sweeps across the top of the screen.
Plot hole: In episode 4, we're informed that Susan and Sabetha traded their travel dials for firewood, and Ian trades his for furs. They do not take them with them into the caves later on. This only appears to make sense from an out-of-universe perspective: Terry Nation needed the characters to part with their travel dials, so they couldn't have just escaped after collecting the key.
Plot hole: The Doctor says he used the fast return switch to take them back to 1963; however, the last place the TARDIS had been before landing on Skaro was 100,000 BC.
Revealing mistake: When Barbara first uses her wrist transporter, Ian steps towards her. As his hand enters the black half of the screen, it disappears.
Character mistake: A Sensorite says, "Give my Doctor the congratulations," instead of "Give the Doctor my congratulations," in the fourth episode.
100,000 BC - S1-E1
Visible crew/equipment: The studio ceiling and lights are visible at several times during the console room scene.
Continuity mistake: Drill marks are visible on the door before Maitland uses the drill on it.
The Daleks - S1-E2
Continuity mistake: The Doctor removes his coat and it's left in the prison cell but in the brief shot of the Doctor and Barbara pushing Dalek Ian, the Doctor is inexplicably wearing his coat again.
Visible crew/equipment: When the Doctor and Ian enter the house in episode one, there is a shadow of the camera on the wall next to Ian.
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