Planet of the Spiders - S11-E5
Revealing mistake: In episode three, when Tommy peers into the room where the Doctor and Sarah are talking to Cho-Je, the camera moves forward - and bumps into a wall with an audible thud and noticeable jerk.
Planet of the Spiders - S11-E5
Continuity mistake: In episode two, Lupton steals a boat, throwing the pilot into the water. Moments later, we see him struggling with the pilot again - who is perfectly dry.
Planet of the Spiders - S11-E5
Revealing mistake: At the very beginning of episode four, the thin pole moving the queen spider can be seen.
Planet of the Spiders - S11-E5
Revealing mistake: In episode one, when a psychic wind is blowing everything all over the Doctor's lab, look for the hatstand standing steady as a rock.
Planet of the Spiders - S11-E5
Revealing mistake: A bad CSO match up occurs in episode one, when Clegg is making the breakfast tray float across the room. The Brigadier is looking at a point some distance from the CSO'd tray.
Planet of the Spiders - S11-E5
Revealing mistake: When Mike and Sarah are in Mike's car going to the monastery, the car swerves off the road and Mike is replaced by a stunt man.
Chosen answer: The Master is insane. If he can't control the universe, he'd rather see it destroyed.
Captain Defenestrator