Visible crew/equipment: Episode 1: After Sarah teases the Doctor a bit when he's being somewhat moody, just as the TARDIS is suddenly thrust off its flight path (which was back to UNIT), Sarah and the Doctor are thrown about in the wonky console room (because the camera turns sideways), and the second camera becomes visible at the left side of the screen.
Revealing mistake: (Part 4) After Omega takes off his mask and looks in the mirror, when he sees that his physical body doesn't exist he puts his mask back on and screams, but when he shouts, "If I exist only by my will, then my will is to destroy," Omega's mask pops up off his face, and we can see the actor's blackened face as he shouts the last bit of his dialogue. (00:07:10)
Planet of the Spiders - S11-E5
Plot hole: At the climax of episode 2, the Doctor is about to catch Lupton when the latter simply teleports to safety. So why didn't he do that in the first place, before engaging in a 15-minute chase?
Mission to the Unknown - S3-E2
Plot hole: The Daleks announce their secret plan on the city's external loudspeaker system, where Cory hears it. It can hardly be a 'secret' plan if it is broadcast for all to hear...
Plot hole: The Brigadier says UNIT HQ is 'a Top Secret establishment'. It is, in fact, so secret that it has a large sign outside informing the world not only of its function, but also the name of the commanding officer.
Marco Polo - S1-E4
Factual error: The story is set in 1289, when Marco Polo was anxious to leave China against Kublai Khan's wishes, so what's Polo doing on the Pamir Plateau?
100,000 BC - S1-E1
Revealing mistake: Susan is supposed to be running through a forest. It is painfully obvious that, in fact, she is simply running on the spot against a back-projected film, and the branches that hit her are simply studio stagehands, hiding just out of shot, hitting the actress with twigs.
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.
Revealing mistake: You can see the studio floor in the "white void" outside the TARDIS door in early shots during episode one of this story.
Marco Polo - S1-E4
Factual error: "Peking" is mentioned several times in this story, but this is an anachronism - this story is set in the year 1289 when Peking (now called Beijing) was known as "Khan-balik".
The Daleks - S1-E2
Visible crew/equipment: About 90 seconds into Episode Two, the shadow of the boom mic crosses Ian's face. (00:01:29)
Earthshock - S19-E6
Plot hole: The Cyber Leader states that he needs the Doctor to pilot the TARDIS. It makes no sense then, that he would try to kill the Doctor once inside, and before the TARDIS had landed in a safe place. (01:33:55)
100,000 BC - S1-E1
Continuity mistake: When Ian and Barbara enter the TARDIS for the first time, Susan operates the door switch. Later on, when the Doctor electrocutes Ian, he uses the exact same switch.
Plot hole: Yartek tried to disguise himself as Arbitan by wearing Arbitan's robes and pulling the hood over his giant rubber head. Strangely enough, no-one seems to notice that "Arbitan" is now suddenly speaking with a completely different voice, and now has a two-foot-tall-head.
100,000 BC - S1-E1
Character mistake: When Ian is trying to escape from the TARDIS in episode 1, he says, "He closed the door from over there, I saw him." It was in fact Susan who closed the door.
Visible crew/equipment: (Ep. 2) When The Doctor, Jo, and Dr. Tyler are taken into Omega's palace, in the first shot of the multiple passageways (right before Jo says that it looks like Aladdin's cave) the curved chalk actor's mark is visible on the floor, then we see it again in three following shots. Note that when they're all escorted further inside, just as Dr. Tyler comments about the matter/anti-matter not making sense, Jon Pertwee looks down, presumably to make sure he hits his mark.
Marco Polo - S1-E4
Continuity mistake: The caption slide at the end of episode two reads: 'Next Episode: The Cave of Five Hundred Eyes'. While the title slide comes up at the start of episode 3, it simply says "Five Hundred Eyes".
Suggested correction: The original episode survives only as audio, so this mistake, if correct, must apply to one of the reconstructed versions (either telesnaps or animation), which probably therefore needs specifying.
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.
The Daleks - S1-E2
Visible crew/equipment: The boom mic shadow makes an apperance in Episode Two, moving across the console as the Doctor suggests abandoning Barbara.
Revealing mistake: In a few UNIT stories you can see where BBC TV badges have been on the UNIT land rovers.
