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.
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.
Continuity mistake: Susan's socks disappear during the opening credits.
Audio problem: During Hartnell's big speech about the creation of a solar system, a cough can be heard from off-stage.
Visible crew/equipment: When Susan runs out into the console room in a panic, the shadows of two crew can be seen on the wall.
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.
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?
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".
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.
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.
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.
Revealing mistake: In episode one, the Voord that falls down the pyramid shaft is very obviously a cardboard cutout.
Visible crew/equipment: In episode one, when the Doctor is near the pyramid, Ian's leg can be seen just before the shot ends, as the consecutive shots used the same section of wall.
Continuity mistake: In episode one, Barbara activates her travel dial only seconds before the others. But in episode two, she's been at Morphoton for quite some time - long enough to change clothes, pick fabrics and get food.
Visible crew/equipment: In episode one, when Ian is first seen inside the pyramid, someone stumbles through the background. Some have claimed this is Barbara, but it happens too fast to tell.
Visible crew/equipment: In episode one, when a Voord falls through a pyramid door, a stage hand can be briefly seen on the other side.
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.
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.
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.
The Aztecs - S1-E6
Other mistake: During the sacrifice scene, the camera bumps into some scenery and suddenly lurches.
