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)
Plot hole: Just after the Doctor meets the Brigade Leader, he looks at the countdown and says in a very loud voice, "only 3 hours and 22 minutes". Several minutes later, when he leaves the office after stunning Benton, the countdown still reads 3 hours and 22 minutes. Did the countdown clock stop? (00:15:10 - 00:22:10)
Continuity mistake: This story starts off where the previous story ('The Dominators') finished, but Jamie says something completely different to alert the Doctor to the approaching lava flow.
Visible crew/equipment: In episode 2, as K-9 seals the wall panel, watch out for the hand which emerges to hold it in place.
Continuity mistake: The Doctor's scarf vanishes while he's detained in the crew's quarters.
Genesis of the Daleks - S12-E4
Continuity mistake: The Doctor's big brown overcoat was taken by the regular Kaled army in episode one and disappeared. In episode six, the Doctor goes into the incubator room and comes out with his brown overcoat magically restored.
The Daemons - S8-E5
Continuity mistake: The hoofmarks seen by both Yeats and Benton from the helicopter appear to be huge when seen from the air. Yet, when the helicopter lands, the hoofmarks are suddenly much, much smaller.
Plot hole: When the airlock door is opening at the end of the final episode, the Cyberman is the only one who appears to be affected by the air rushing out. Although 'rushing out' is probably overstating the speed of the 'explosive decompression'. It's not so much an explosion as a gentle breeze...
Continuity mistake: In episode 1, when the Doctor opens the garage doors with his 'door handle', note the two men in the background, the position of the car behind him and the white pillar. In the next shot, the men and pillar disappear and the car moves to a different spot. In the shot after that, the tanker truck is now parked in front of a pillar. You can see near the beginning of episode 3 that there are two entirely different buildings that the tanker had been filmed in front of. (00:14:25)
The Dalek Invasion of Earth - S2-E2
Audio problem: When the Doctor says that what they're seeing now is the middle period of Dalek history, you can hear a metallic thing being dropped off screen.
Deliberate mistake: Tom Baker has some wounds on his lip (caused by actor Paul Seed's dog) which appear in episode one and four in the TARDIS scenes and disappear for the rest of the episode.
Visible crew/equipment: In episode two, the shadow of the boom mic crosses Jon Pertwee's head as he's giving the "epsilon coordinates" to Liz.
Remembrance of the Daleks - S25-E1
Visible crew/equipment: At the beginning of the episode when the soldier is thrown back after being exterminated, the wire pulling him is very visible.
The Ambassadors of Death - S7-E3
Continuity mistake: There are a handful of similar continuity errors, but one that stands out in particular occurs at the end of Episode 1. The Doctor and Liz go into the lab and Taltalian steps out from behind the door wearing glasses and brandishing a gun. However, in the recap at the start of episode 2 he isn't wearing glasses and moves differently.
Visible crew/equipment: In episode four, when the Doctor is congratulating himself on blowing up the Swarm, the shadow of a boom mike can be seen.
Plot hole: After the Doctor and Leela's clones fade, the camera pans to show Leela's knife. But since the knife was created in the cloning process, it should have faded out with Leela, the Doctor and their other personal items.
Continuity mistake: In episode three, the readout strip dangling from K-9's mouth shortens between when he shoots the infected crewman and shoot Leela.
Revealing mistake: In episode 6, during the generally poor fight sequence between the Brigade Leader and Greg Sutton, Greg's first punch to the face misses the Brigade Leader by miles. (00:19:10)
The Caves of Androzani - S21-E6
Revealing mistake: It's already been mentioned that Peri bounces off a mattress, but watch what happens when the Doctor walks over to see if she's all right. The 'cave' floor visibly moves under his foot.
Resurrection of the Daleks - S21-E4
Revealing mistake: When Lytton and his men approach the self-destruct chamber in episode three, the door is closed in front of them. It wobbles as it closes.
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