The Impossible Planet (1) - S2-E11
Factual error: The Doctor (and the staff on the station) refer to the idea of a planet being in orbit around a black hole as 'impossible'. It is not. Gravity (and physics in general) works perfectly well outside of the event horizon. For all practical purposes - regarding orbiting around it - the black hole might as well be any other object, as long as it has an equal mass. (00:07:15 - 00:08:30)
The Impossible Planet (1) - S2-E11
Continuity mistake: When the Doctor and Ida descend into the core of Krop Tor, the screen charting their progress shows 39% Oxygen. After cutting away to an overhead shot of the two, the camera cuts back to the same descent display, only now the oxygen percentage (which has been descending constantly all this time) is at 42%. (00:35:25)
The Impossible Planet (1) - S2-E11
Factual error: Ida, the science officer, says that the planet is in geostationary orbit around the black hole. However, the word "geostationary" applies very specifically to objects orbiting the planet Earth. Since a black hole is a type of star, this planet's orbit could be described as astrostationary, or even just stationary, but definitely not as geostationary. A science expert on an interstellar mission wouldn't make this mistake, and she wasn't dumbing things down, either, since "geostationary orbit" is already a pretty obscure topic for people unfamiliar with space technology. (00:07:40)
The Impossible Planet (1) - S2-E11
Factual error: The graphics depicting the black hole show matter falling directly towards the centre of it. This would only happen if all the matter happened to be heading in that direction already. In reality, matter approaching the black hole at any other angle would swirl around the event horizon, like water going down a plughole.
The Impossible Planet (1) - S2-E11
Other mistake: When the Doctor asks what the planet is called, Ida says, 'Don't be stupid, it hasn't got a name, how could it have a name?' A few minutes later, she tells the Doctor the planet is called 'Krop Tor'.
The Impossible Planet (1) - S2-E11
Continuity mistake: In shots of the base's Ood habitation area from above, the Ood are shown in four rows from left to right, with the Ood in the third row standing with their backs against the room's middle partition and the other rows sitting on benches. However, in a shot from inside the lower area when the Doctor and Rose first go to Ood habitation, the third row is shown sitting as well. Not until later in the episode, when Danny is ordering the Ood to remain in the room, is the third row shown standing again. (00:25:15)
The Impossible Planet (1) - S2-E11
Continuity mistake: When the underground cavern is first shown, the descent pod is at the bottom of a pile of rubble up against the wall at the bottom of the drilled shaft. However, in the shot of the cavern shown when Ida says "My god, that's beautiful," the pod and pile of rubble is further away from the wall. (00:37:00)
The Impossible Planet (1) - S2-E11
Continuity mistake: When Rose is talking to Danny about the Ood, in one shot she's holding her cup with two hands, only for her to be holding it with only one hand in the next shot. (00:11:25)
The Impossible Planet (1) - S2-E11
Continuity mistake: When Rose takes out her phone and finds there's no signal, she slides it open twice, in the wide shot and close-up. (00:23:15)
The Impossible Planet (1) - S2-E11
Continuity mistake: When Rose, the Doctor, and the others are running across the walkway a stream of steam appears and disappears between shots. (00:03:55)
The Impossible Planet (1) - S2-E11
Plot hole: The Doctor and Ida are stranded 10 miles down, and yet the lift travels very slowly, like walking pace. They only have an hour's worth of oxygen left in their suits - by the time they get to the surface, it would have run out.
The Impossible Planet (1) - S2-E11
Plot hole: The rocket flew down a gravity funnel and (presumably) crash-landed on the planet, since the true Captain died during the landing. The rocket is big, but surely not large enough to contain all the 'flat-packed' materials for the sanctuary base (which is massive) and the gantry which supports the rocket. Where did that gantry come from? It is the same size as the rocket. It is not possible that the sanctuary base and rocket gantry could have fitted on board that rocket.
The Impossible Planet (1) - S2-E11
Continuity mistake: After Ida retracts the roof to show the black hole, there is a shot where the Doctor and Rose are looking at it, with nothing above them, as he explains about it. However, other shots of the base's control room show that there are things in the room, such as wires connecting the central computer table to the walls, that should have been visible. (00:08:00)
Chosen answer: 1) When Stephen Moffat took over he ignored a lot of what had been developed before (there is not in-universe answer). 2) It would have killed Rose, so the Doctor absorbed the energy. His body regenerated before the energy could do a significant amount of damage that would prevent regeneration.