The Daleks - S1-E2
Plot hole: Why does The Daleks' prison have beds? The Daleks don't need them and clearly state that they have no idea what the Thals look like, speculating that they are "horribly mutated".
Plot hole: Yartek tried to disguise himself as Arbitan by wearing Arbitan's robes and pulling the hood over his giant rubber head. Strangely enough, no-one seems to notice that "Arbitan" is now suddenly speaking with a completely different voice, and now has a two-foot-tall-head.
Plot hole: The miniaturized TARDIS crew never interact with the other characters in this story, because, as the Doctor points out, the 'giants' will be unable to hear them, as their voices will be on a different wavelength. So why does the Doctor later suggest using the telephone to try to call for help?
Mission to the Unknown - S3-E2
Plot hole: The Daleks announce their secret plan on the city's external loudspeaker system, where Cory hears it. It can hardly be a 'secret' plan if it is broadcast for all to hear...
Plot hole: It is highly unlikely that the discovery of a dead down-and-out's body in an empty warehouse would be reported in a national newspaper, especially as the discovery had to have been made when the newspapers were already being printed.
Plot hole: We twice see a map of how far the ice is away from the house, once in the first episode, and later in episode five. The ice has moved most of the way across the map in this time, and the distance it has moved is stated to be a 100 metres. This would place it only 20 metres from the base. The problem with the distance is that it takes Penley quite a while to get the injured Jamie to the base, including a stretch across open ground. Also, The Ice Warriors weapon targeter suggests the base is as much as two kilometres away. So just how far away is the ice; 20 metres, 2 kilometers...or somewhere in between?
Plot hole: When the airlock door is opening at the end of the final episode, the Cyberman is the only one who appears to be affected by the air rushing out. Although 'rushing out' is probably overstating the speed of the 'explosive decompression'. It's not so much an explosion as a gentle breeze...
Plot hole: When Jamie and Cully go on the offensive, Jamie lures a quark away from a drilling site into a narrow valley, then Cully drops a boulder onto it. Yet when we see the crushed quark, it is next to a drill, on flat land.
Plot hole: Despite being asked to memorise all the locations and war zone commanders, Zoe's photographic memory lets her down: her first words to the Mexican leader are 'Who are you?'.
Plot hole: Just after the Doctor meets the Brigade Leader, he looks at the countdown and says in a very loud voice, "only 3 hours and 22 minutes". Several minutes later, when he leaves the office after stunning Benton, the countdown still reads 3 hours and 22 minutes. Did the countdown clock stop? (00:15:10 - 00:22:10)
Plot hole: Jo is surprisingly skeptical about the TARDIS being able to move, considering she saw it dematerialise in the last episode.
The Daemons - S8-E5
Plot hole: It is never explained who - or what - killed the man in the churchyard during the first scene (early in part one). It cannot be Bok (the gargoyle) or Azal (the Daemon) as neither of them have awoken.
The Curse of Peladon: Episode One - S9-E5
Plot hole: The delegate Alpha Centauri is a 'hexapod' - a creature with six legs and feet. ('Hex' = "six", 'pod' = 'foot'.) But throughout this Doctor Who story, Centauri can be seen with all six legs and feet in the air, projecting from the front of the creature... so what is it walking around on?
The Sea Devils: Episode Four - S9-E12
Plot hole: The Doctor and the Master both surface in bright orange diving suits and are the only two wearing them. But when the supposed body of the Master is dragged out it is also wearing an orange diving suit, and the Doctor and Master are still wearing theirs, so a third suit appeared from nowhere.
Plot hole: The Brigadier says UNIT HQ is 'a Top Secret establishment'. It is, in fact, so secret that it has a large sign outside informing the world not only of its function, but also the name of the commanding officer.
Plot hole: After UNIT HQ disappears, you can see a patch of grass where the UNIT HQ used to be...but just exactly how can grass grow underneath a building?
Plot hole: 10,000 Daleks sounds impressive but it wouldn't be enough to invade a planet, let alone an entire galaxy.
Plot hole: Professor Jones says they tried to borrow the cutting equipment a few weeks ago, but Mr. Stevens says it was yesterday. One of them must be wrong...
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