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".
Audio problem: In episode 3, when the Doctor is squaring off against the drooling madman, it's clear in most of the shots that the sound of the madman's panting is not reflected in his facial and body movements. (00:10:20)
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.
Other mistake: I know that regeneration causes the Doctor to change his appearance, but I didn't know it can produce a tattoo visible on the Doctor's right arm in episode 2.
Character mistake: When the Brigade Leader shoots the Primord, he noticeably closes his eye. He is supposed to be a high ranking well trained officer.
Answer: TARDISes are generally available for properly authorised use on Gallifrey; they're not usually assigned to a particular Timelord on a long-term basis. The Doctor stole his when he left his homeworld.
Tailkinker ★