Continuity mistake: When the Doctor is listing questions about what exactly the ghosts are, he goes from gesturing with his left hand in the close-up to gesturing with his right in the wide shot. (00:17:17)
Continuity mistake: Missy's cameo brooch is unpinned and hanging askew when she vaporizes Osgood, but the brooch rights itself and is pinned properly when Missy steps on Osgood's eyeglasses. (00:23:00)
In the Forest of the Night - S8-E10
Continuity mistake: When Clara is looking at the drawing in Maebh's homework book while the Doctor tells her about the solar flare, her grip on the book changes between shots. (00:22:44)
Continuity mistake: During the early scene with the Cybermen outside St Paul's, when Missy pulls out her phone/disintegrator weapon and shows the Doctor pictures of the Cybermen going viral all over the planet, and when she prepares to take a picture of the two of them, her grip on the device, as well as which hand she's holding it in, keeps changing between shots. (00:03:00)
Continuity mistake: When Missy orders her Cybermen to blow up the plane and kill some Belgians, her control bracelet is missing from her wrist in one shot. (00:33:54)
Mummy on the Orient Express - S8-E8
Continuity mistake: When the Doctor phones Clara and discovers she's trapped in the locked car with Maisie, his phone keeps switching hands. (00:21:55)
Continuity mistake: When Courtney comes into The Caretaker's room in search of paper towels, there is a "keep out" sign (reading "Go Away Humans") hanging in the window of the inner door. When the Doctor is talking to her just before she leaves, the sign is missing. Over the course of the rest of the episode, the sign proceeds to appear and disappear a few more times. (00:15:50)
Time Heist - S8-E5
Continuity mistake: Near the end, when the Doctor and Clara are standing by the TARDIS on the planet they took the Teller and its mate to, Clara's hands go from touching the buttons on her jacket to loosely clasped lower down. In the third shot of her, they return to the first position. (00:44:28)
The Day of the Doctor - S7-E16
Continuity mistake: After Clara enters the Doctors' cell, and they're talking about how the door was unlocked, shots inside the cell show the door about halfway closed, while a shot from outside looking into the cell shows the door wide open. (00:45:25)
The Day of the Doctor - S7-E16
Continuity mistake: During the scene in the barn where the three Doctors have their hands on the button, when Eleven notices Clara crying and asks her what's wrong, the Doctors' hands go from stacked on top of each other on the button to only touching it with their fingers. (01:02:40)
The Name of the Doctor - S7-E15
Continuity mistake: When the Doctor is talking to River just before entering his own timeline to rescue Clara, in the shots facing him, the glowing column representing his timeline is not visible, despite the fact that a wide shot reveals he's standing right in front of it. (00:39:25 - 00:40:04)
Journey to the Centre of the TARDIS - S7-E12
Continuity mistake: When the Doctor is asking Clara if she feels safe in the last scene, most of her hair is draped over her left shoulder. However, whether some of her hair is draped over her right shoulder or not changes between shots. (00:45:05)
Journey to the Centre of the TARDIS - S7-E12
Continuity mistake: Near the end, when the Doctor picks up the remote control and reads the words written on it, the position of his hands as he's holding the device changes between the close-up and the wide shot. (00:43:40)
Continuity mistake: When Clara draws the Doctor's attention to the vision of a forest appearing in the archway, the candelabra she is holding has two candles in it, with the third hole empty. Moments later, after the apparition has disappeared, there are now three candles in it. (00:15:30)
Continuity mistake: For most of the episode, there is a thunderstorm going on at Caliburn House. However, when the TARDIS is seen dematerializing and rematerializing when the Doctor and Clara go to take pictures of the ghost throughout time, it's dry in the grove where it was parked. The first time is especially noticeable, as moments later we are shown Professor Palmer and Emma looking through a rain-spattered window, commenting on the noise of the TARDIS' engines.
Deep Breath - S8-E1
Continuity mistake: Vastra hands the police inspector a bag of sonic lanterns, to be used to contain the T. Rex. In the next shot, looking at the TARDIS on the riverbank, he's not holding it. (00:02:15)
In the Forest of the Night - S8-E10
Continuity mistake: When Clara mentions worrying about a witch in a gingerbread house while she and the Doctor are searching for Maebh, the phones she is holding switch hands between shots. (00:20:11)
Continuity mistake: During Clara's first conversation with Danny, the folders in her hands are unmarked in close-ups, but have labels on them in wide shots. In addition, the folders and newspaper she's holding keep changing position between shots. (00:07:30 - 00:08:26)
Continuity mistake: When the Doctor shows Clara the "listen" written on one of his blackboards, the handwriting is different to when it was first shown. (00:07:07)
Continuity mistake: The leaf Clara feeds the Old God, which was the catalyst for her parents meeting and which she kept tucked in her book as "page 1", looks completely different to its first appearance in "The Bells of Saint John".
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.