Continuity mistake: Towards the end of episode 2 it's nighttime, but when Ian and the Doctor lure the Dalek over from the TARDIS, and when it falls, it's daylight.
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.
The Daleks' Master Plan - S3-E4
Visible crew/equipment: In Episode 2 when Marc Cory and the other Ambassador are talking, a figure who appears to be wearing Space Security Uniform (and this isn't Nicholas Courtney) and a stage hand walk by, and you can also see the end of the set.
The Daleks' Master Plan - S3-E4
Continuity mistake: In the cliffhanger to episode 1 of this story, as The Daleks approached the TARDIS, the TARDIS door was open. At the beginning of episode 2, seconds after the cliffhanger moment in 1, the door is suddenly closed. (00:01:00 - 00:02:00)
Revealing mistake: When the Keeper is on the TARDIS, he asks to borrow the screen. But on the upper left corner, you can see it over where it's meant to be.
Plot hole: In "The Five Doctors", Susan tells Turlough that she can pilot the TARDIS to some extent. During series 1 and 2, it was clear that she couldn't pilot it at all. She couldn't have been taught between episodes as the Doctor had little idea himself at the time.
Revealing mistake: When K-9 is cutting through the wall of the hut, the cut overtakes his laser at one point.
Invasion of the Dinosaurs - S11-E2
Revealing mistake: When the Brigadier is using a flare to ward off a dinosaur in the tunnel, the smoke instantaneously vanishes as it hits the split screen.
Other mistake: In part one, one of the gunmen shoots at a bottle behind the bar and it takes several seconds for the bullet to travel only a few feet.
Visible crew/equipment: At the beginning of episode two, the Doctor finds Ian unconscious with a very obvious shadow of the camera and cameraman looming over him.
Visible crew/equipment: At the end of episode 3, a venom grub starts chasing Ian. As it enters the screen however, you can see the actor under it crouching down.
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.
Castrovalva - S19-E1
Deliberate mistake: The newly regenerated Fifth Doctor is wearing completely different shoes than the Fourth Doctor did in the previous story. This is deliberate. The boots worn by the Fourth Doctor were actually privately owned by actor Tom Baker. Still, a mistake but this is why.
The Sontaran Experiment - S12-E3
Continuity mistake: In Episode 2, when the Doctor calls Harry from the Control Room and Harry enters the room next to the Cryogenic Chamber, there is an oblong yellow panel next to the door. It extends from about Harry's waist line to about 200mm below the top of the door. But in Episode 3, when Noah calls Vira from the control room part way into his transformation, and everyone runs into the adjacent room, the panel is mounted differently. It now extends from about Harry's mid-torso, to the top of the door frame. (00:03:35 - 00:09:32)
Continuity mistake: In "The Deadly Assassin" the Doctor's blood is red but in "State of Decay" his blood is suddenly dark blue. Then it's back to being red in "The Two Doctors."
The Creature from the Pit - S17-E3
Plot hole: In part 2 it's brought up in conversation several times that all metal is rare on that planet. Handy exposition for the viewers, but it's in fact a really odd thing for the characters to say. The inhabitants aren't giving a tour of their planet (certainly not deliberately at any rate), so why would they state facts that have been well known to them all of their lives? It's a bit like meeting strangers and informing them that two thirds of the Earth are covered by oceans.
Revealing mistake: Whenever the TARDIS's scanner picture of the Doctor's laboratory is shown, the TARDIS itself is always in the picture.
Revealing mistake: When the resistance are storming the landing bay, one of them punches at least a foot to the right of a guard's face, but he still collapses.
Visible crew/equipment: In an early TARDIS scene, at one point the cable powering the console is seen running from the base and under the wall.
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