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)
The Christmas Invasion - S2-E2
Continuity mistake: When Mickey is explaining what pilotfish are, after looking it up on his computer, in most of the shots he's gesturing with his left hand, but there's one shot where he's using his right hand. (00:14:10)
The Christmas Invasion - S2-E2
Continuity mistake: When Daniel Llewellyn meets Harriet Jones, she pulls out her ID card when she introduces herself. The scene cuts to a shot of Llewellyn saying that he knows who she is, and when it cuts back to Harriet, the ID card has vanished without her making any movement to put it away. (00:16:10)
The Christmas Invasion - S2-E2
Continuity mistake: When Rose goes to look at the Doctor in bed while Harriet is speaking on TV, the bedding has changed from when it was previously seen. (00:28:05)
The Parting of the Ways (2) - S1-E13
Continuity mistake: At the beginning of the scene where Rose, Jackie and Mickey are in the restaurant, in the wide shot, Rose moves her left hand to the side of her head, while looking down with her head facing towards the other side of the table, which her elbow is resting on. In a close-up immediately afterwards, she's looking out the window with her hand to her face and her elbow resting on the windowsill. (00:18:50)
Revealing mistake: When the Gamestation's transmissions are cut off by solar flares, there is a close-up of a screen going over to static. In the upper right corner, a box with "Play" written in it is visible, revealing the image on the screen as a video. (00:34:50)
Other mistake: After Jack uses Davitch's information to complete the Controller's coordinates, the Doctor uses a remote to project a holographic, transparent screen of the location in question. The image shows Orion's Horsehead and Flame Nebulae. In a shot immediately afterwards, looking through the holo-screen back at the Doctor and company as he explains what's going on, the image of the nebulae is not mirror-reversed as it should be, but is the same orientation as in the previous shot. The kicker is that the image of the nebulae has been altered, as well: it's already been mirror-reversed - in the actual sky, the Flame is left of the Horsehead. (00:38:40)
The Doctor Dances (2) - S1-E10
Continuity mistake: When the Doctor is looking at Rose's hands, turning them over repeatedly, while she's describing how she was hanging from a barrage balloon, there's one moment where her hands are turned palm-up in a shot facing her, but back-up in a shot facing him. (00:18:25)
Continuity mistake: When the Doctor meets Nancy, when she warns him not to answer the TARDIS' ringing (fake) door phone, in a shot facing her he's holding his jacket away from his chest, but in the next shot facing him that hand is empty. (00:06:55)
Continuity mistake: When Jack is scanning Rose onboard his spaceship during their conversation, he leans against a metal railing in front of The Pilot's seat twice, in two successive shots. (00:20:40)
Continuity mistake: During the Doctor and Nancy's conversation at her hideout, in shots facing her there is a bright circle of light cast on the wall to her left, which her shadow partially overlaps. In shots facing the Doctor where both him and Nancy are visible, the circle is gone, and Nancy's hideout is noticeably more dimly lit. (00:23:15)
Father's Day - S1-E8
Continuity mistake: When Rose checks her messages while riding in Pete's car and hears the very first phone call instead, the positions of her fingers change between the wider shot and the close-up. (00:13:30)
Continuity mistake: When the Doctor is restrained by two of the Editor's corpse minions, and the Editor demands to know who he is, the hand of the one holding the Doctor's right arm moves between his chest and shoulder several times. (00:30:50)
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.