Revealing mistake: The footage of Kroll eating Harg is obviously reversed, as evidenced by the fact that the smoke from the pipe is heading into it, whereas in every other shot it's flowing out of it. (00:23:00)
Visible crew/equipment: The boom mike can be seen in the first scene set at the stones in the upper right corner of the screen.
Continuity mistake: During Kroll's attack on the refinery, several pieces of the refinery get broken off and then reappear in subsequent shots.
Revealing mistake: One of the stones wobbles when a crow lands on it in episode one.
The Armageddon Factor - S16-E6
Continuity mistake: In episode 2, just after K-9 begins blasting the door, look behind Romana and notice that you can see the TARDIS - which supposedly left in the previous scene.
The Armageddon Factor - S16-E6
Plot hole: In episode four, Merak expounds on how only the Doctor and Romana can get into the TARDIS, despite the fact that he shouldn't even know what the TARDIS is. His insight continues in episode six, where he talks knowledgeably of the sixth segment of the Key to Time, despite having been told nothing about it.
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