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)
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.
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 a few UNIT stories you can see where BBC TV badges have been on the UNIT land rovers.
Revealing mistake: When the Doctor sabotages the inertia neutralizer, the wall wobbles.
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: 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 supposedly heavy statue Ian drops down the lift to destroy the pursuing Dalek in episode four wobbles when he first touches it.
Revealing mistake: In episode one, the Voord that falls down the pyramid shaft is very obviously a cardboard cutout.
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.
Earthshock - S19-E6
Revealing mistake: When the Cybermen break through to the bridge, they brush against the door and it bends as if made of cardboard. It was supposed to be made of reinforced steel. (01:09:10)
The Tomb of the Cybermen - S5-E1
Revealing mistake: When Kaftan is activating the revitaliser controls, you can see Patrick Troughton moving into position for when he runs and grabs her.
Revealing mistake: In order to save money filming the lift-off of Crayford's rocket from Oseidon, the producers decided to use stock footage of a Saturn 5 blast-off. Unfortunately, that meant the words "UNITED STATES" in large red lettering are seen on the side of the rocket...which is a little bit of a giveaway, especially as the rocket is supposed to be a BRITISH space probe.
Revealing mistake: Watch the scene where Uvanov sticks a Laserson probe into the head of one of the Vocs (V4) as it is strangling the Doctor. After he shoves the probe in, you can quite see the suit's helmet come away from the rest of the suit.
Revealing mistake: When Ace and Susan are sitting underneath the huge pipe about to be executed by the Fondant surprise, it's obvious that the actresses aren't sitting directly underneath the pipe, but slightly behind it.
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: In episode four, when Caber breaks a piece off the Zygon equipment, the entire wall shakes.
Revealing mistake: In the end part of this story, in the large spider's den, the string supporting it is visible.
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