Revealing mistake: In a few UNIT stories you can see where BBC TV badges have been on the UNIT land rovers.
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.
The Daleks - S1-E2
Revealing mistake: In episode one, when Ian notices the breeze, a wide shot of the forest shows the background dropcloth is moving. (00:02:10)
The Daleks - S1-E2
Revealing mistake: The Dalek that Ian hides from in Episode Seven has a bad castor. The flopping of one of its wheels is audible. (00:08:20)
The Daleks - S1-E2
Revealing mistake: In episode six, Ian helps Barbara get a grip on the rock and a piece of the polystyrene pops off in his hand.
The Daleks - S1-E2
Revealing mistake: The supposedly heavy statue Ian drops down the lift to destroy the pursuing Dalek in episode four wobbles when he first touches it.
The Daleks - S1-E2
Revealing mistake: Toward the end of episode two, when Susan opens the TARDIS doors, the console wobbles.
The Daleks - S1-E2
Revealing mistake: In the Dalek city, it is unfortunately obvious that the "tunnels" behind the actors are just photographic blow-ups, as you can see the bottom of the wall meeting with the floor.
The Daleks - S1-E2
Revealing mistake: There are numerous scenes where the background Daleks are blown-up photographs. The most obvious is in episode five when The Daleks are discussing the radiation drugs.
The Daleks - S1-E2
Revealing mistake: When the Thals are using sunlight to blind the Dalek cameras in Episode Six, wide shots of the Dalek city show it moving back and forth from bad matte combination.
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.
Revealing mistake: In episode one, the Voord that falls down the pyramid shaft is very obviously a cardboard cutout.
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 Dalek Invasion of Earth - S2-E2
Revealing mistake: When Barbara is throwing her bombs, she grabs the window frame in front of her, which wobbles alarmingly.
The Dalek Invasion of Earth - S2-E2
Revealing mistake: In episode 1, one of the windows on the TARDIS is leaning in, but by the time we get to episode 6 it has managed to fix itself. Also when the bridge falls down you can see the poster through the gap, showing that there is no back to the TARDIS.
The Dalek Invasion of Earth - S2-E2
Revealing mistake: When Barbara, Jenny and Dortman are running through the deserted streets of London, in the very last shot, if you look to the left of the screen, you can see some people walking down the street.
The Dalek Invasion of Earth - S2-E2
Revealing mistake: When a rebel throws a bomb from the second floor of the Dalek saucer, notice it explodes too early and in the wrong place.
The Rescue - S2-E3
Revealing mistake: At the beginning, as the Doctor is standing in the TARDIS door, the cave wall can be seen through the TARDIS.
Revealing mistake: In the end part of this story, in the large spider's den, the string supporting it is visible.
Revealing mistake: When the robotic Doctor first appears - and in many of the later scenes involving the jungle on Mechanus - it is very obviously not William Hartnell playing him, but a vaguely similar double. In addition, his lines have been dubbed by Hartnell and do not always match the movements of his mouth.
Answer: It was never destroyed on-screen; it was intact at the end of the TV movie, and destroyed by the start of the 2005 series. It was destroyed in the novel "The Ancestor Cell," but in a completely different manner to what happened in the series.
DaveJB