Continuity mistake: In episode 4, the Doctor's bow shrinks from when he talks to Liz Shaw while in prison, to when he stows aboard a jeep later. In the DVD commentary, producer Barry Letts blames himself for this mistake. (00:13:00 - 00:19:50)
Continuity mistake: In episode 1, when the Doctor opens the garage doors with his 'door handle', note the two men in the background, the position of the car behind him and the white pillar. In the next shot, the men and pillar disappear and the car moves to a different spot. In the shot after that, the tanker truck is now parked in front of a pillar. You can see near the beginning of episode 3 that there are two entirely different buildings that the tanker had been filmed in front of. (00:14:25)
The Ambassadors of Death - S7-E3
Continuity mistake: There are a handful of similar continuity errors, but one that stands out in particular occurs at the end of Episode 1. The Doctor and Liz go into the lab and Taltalian steps out from behind the door wearing glasses and brandishing a gun. However, in the recap at the start of episode 2 he isn't wearing glasses and moves differently.
Continuity mistake: At the beginning of the third episode, the countdown reads 49:18:32 in the close up, but when the Brigadier walks across the room it now is on 49:15:01. (In other words three minutes thirty one seconds have elapsed). Yet these two events are about ten seconds apart. Also, the timer should never read either of these times. The professor moved the countdown forward to exactly 49 hours (49:00:00).
Continuity mistake: Throughout the serial, Bessie's tires are dry in studio shots (inside the Doctor's shed) and wet on location shots.
Continuity mistake: Liz's hairstyle is different in indoor and outdoor shots.
The Ambassadors of Death - S7-E3
Continuity mistake: Taltalian's French accent mysteriously gives way to an English one in some shots, most notably on location, e.g. when he catches an escaping Liz and says "Get in Miss Shaw".
The Ambassadors of Death - S7-E3
Continuity mistake: In episode 4 a UNIT sentry (Max Falkner) is seen shooting at one of the ambassadors when he is killed, but in episode 6 he is alive and well and is seen again in the 1976 story "The Android Invasion" , this time as a corporal.
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