Genesis of the Daleks - S12-E4
Revealing mistake: When Ronson is killed by The Daleks, you can see Ronson reacting a little too soon to the Dalek laser. (00:14:40)
The Talons of Weng-Chiang - S14-E6
Audio problem: In episode five, when the Doctor and Leela are in the opium den, the Doctor's lips do not match his spoken dialogue.
Factual error: In episode one, Abraham Lincoln seems to have affected a southern accent and put on some weight.
Time-Flight - S19-E7
Factual error: The Pleistocene Period began around 1.8 million years ago, not 140 million years ago as stated.
Genesis of the Daleks - S12-E4
Revealing mistake: In episode 6, when the Thals detonate the charges, smoke is seen coming through the door before the detonator is pressed down. (00:19:40)
The Caves of Androzani - S21-E6
Continuity mistake: When the Doctor is climbing through the tunnel to the Queen bat, note the question mark on his lapel: the image is reversed.
Earthshock - S19-E6
Revealing mistake: When Lieutenant Scott kills the second Cyberman on the bridge, he starts falling down way too early.
Invasion of the Dinosaurs - S11-E2
Revealing mistake: When Grover and Whitaker struggle over the time machine at the very end of episode six, the console wobbles and jerks as though it were very lightweight.
Audio problem: About 10 minutes into episode 1, the sound of a pencil being dropped and rolling across the studio floor can be heard. (00:10:00 - 00:11:00)
The Sea Devils: Episode Four - S9-E12
Plot hole: The Doctor and the Master both surface in bright orange diving suits and are the only two wearing them. But when the supposed body of the Master is dragged out it is also wearing an orange diving suit, and the Doctor and Master are still wearing theirs, so a third suit appeared from nowhere.
Battlefield - S26-E1
Continuity mistake: When the roof falls on Ace and Shou Yuing, Ace's face gets covered in dark streaks, which mysteriously disappear soon afterwards.
Earthshock - S19-E6
Revealing mistake: The "dead" crewmembers at the end of episode two can be seen breathing.
Revealing mistake: In Episode 3, when Dask is cutting the wires, the second explosion happens too early.
The Caves of Androzani - S21-E6
Revealing mistake: When Peri falls into the spectrox nest, watch for her to reappear as she bounces off a mattress.
Revealing mistake: At the climax, when the Doctor and Sarah are setting up the scarf trap, the Doctor bumps a rock, which wobbles.
Continuity mistake: In Episode 1, the TARDIS crew pass out from the change in pressure as they descend into the Earth. However, at the end of episode four, they climb out on foot and suffer no ill effects.
Revealing mistake: When Jamie is wrestling with one of The Ice Warriors in a storage room, one of them gives the wall an almighty knock and it nearly falls down.
Plot hole: In episode 1, on both occasions that Silas P presents his card (first to Daphne S, then later to the Doctor), he gives it to his victims the wrong way around. They have to surreptitiously turn it over so that the side with his name on it is facing them, and then act surprised when he tells them to flip the card over to reveal the words "Happiness Patrol Undercover", as if they hadn't seen it before.
Other mistake: What happens to Tegan's bag when the plague victim transforms into the cavalier? It doesn't appear to be left behind, even when the cavalier later vanishes.
Other mistake: In episode 3, watch the scene where the co-pilot is shooting; you can see his pants rip straight down the seam at the back - which unfortunately happens to be the part of him facing the camera at the time. He then wanders around for most of the rest of the episode with the tear in his pants plainly 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