Continuity mistake: When the Isolus leaves Chloe, in the shot facing Chloe where it says goodbye, Chloe's hand is raised to the wall, where the two were drawing a picture of the Earth. In the wide shot where the Isolus leaves Chloe's mouth, her arm is lowered. In the next close-up of Chloe, when she says "Mum?", her arm is raised again. (00:36:05)
Continuity mistake: When the Doctor first appears in the episode, baiting the Hoix with a piece of raw meat, the meat turns around in his hand between the close-up and the wide shot. (00:02:30)
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)
Continuity mistake: When the Doctor is in the cage with the faceless people, his flashlight switches from his left hand to his right hand and back. (00:18:25)
Continuity mistake: When Jake turns on the light in the cabinet with the Cyberman on the zeppelin's bridge, he's holding his handgun in his left hand. The scene cuts away to Mickey briefly, and when it cuts back to Jake his gun has jumped to his right hand. (00:24:30)
The Girl in the Fireplace - S2-E7
Continuity mistake: For most of the scene where he's probing Reinette's mind to find out what the clockwork droids want with her, placing his hands on her temples, the Doctor's left hand is positioned with two fingers on either side of her ear. When he realises that she's seeing some of his memories, his ring finger has jumped to being in front of her ear, without him taking his hands from her head. (00:20:50)
Continuity mistake: During the Doctor and Sarah Jane's conversation in the café, when Sarah says that she missed him and he responds that she was getting on with her life, in a shot facing Sarah, the Doctor's hands are not visible repairing K9. In the next shot, facing him, his left hand is suddenly on the robot, in a position where it should have been visible in the preceding shot. (00:17:45)
Continuity mistake: When Mickey pulls the blanket off K9 and turns him on to ask if he has anything to get them inside the locked school, K9's right side panel is missing, exposing the wires and circuitry inside him. When he turns up in the cafeteria to help the others escape the Krillitanes, the missing panel has suddenly appeared. (00:34:10)
Continuity mistake: When Sarah Jane breaks into the school, she has her purse with her. However, after she runs out of the hall with the headmaster's office after hearing some unsettling noises, it disappears, as she no longer has it when she finds the TARDIS hidden in a storage room off the gym.
Continuity mistake: During the Doctor and Sarah Jane's conversation in the café while he's repairing K9, when Sarah mentions the events of "The Christmas Invasion" and the Doctor confirms that he was there, the Doctor's hold on a piece of wire from K9's insides changes between shots. (00:17:20)
Continuity mistake: When Cassandra, after possessing Rose, is checking out her new body in a mirror, when she starts jiggling up and down, her right hand changes position between shots of her and shots of her reflection. (00:13:40)
Continuity mistake: When Cassandra, possessing Rose, answers her phone, as Chip is telling her that Rose's accent is "Old Earth Cockney", she puts the phone to her ear twice. (00:14:55)
Continuity mistake: When Cassandra reveals her presence to the Doctor, she starts off by turning him to face her, then pulling his tie out of his jacket with her right hand and tightening the knot with her left hand, in a shot facing him. In the next shot, facing her, she has her right hand holding the knot of the tie. Finally, just before Cassandra reveals her identity to the Doctor, shortly later, which hand is holding the tie changes again. (00:23:20)
Continuity mistake: When Cassandra, possessing Rose, confronts the Doctor after he wakes up in one of the clone pods and tells him how she intends to kill him, her hand changes position between the shot from inside the pod, when she rests her hand on the front, and the next shot from outside the pod. (00:24:20)
Continuity mistake: When the Doctor is attaching the ring device to the elevator cable, the position of his hand as he's holding it in place changes. (00:34:10)
The Christmas Invasion - S2-E2
Continuity mistake: When the TARDIS crash-lands at the beginning, it comes to a halt in a corner of the Powell Estate's courtyard, by the garbage containers. Later, when Rose is watching through the window as blood-controlled people walk through the courtyard, the TARDIS has moved further out into the plaza. (00:23:05)
The Christmas Invasion - S2-E2
Continuity mistake: At the beginning of Rose and Jackie's conversation in the kitchen about the Doctor, Rose takes a piece of food out of the fridge. Moments later, when she rests her hand on the light switch by the door, it has vanished. At no point in the intervening time did she come anywhere near a spot where she could have put it down, and she didn't eat it either. (00:04:10)
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.