Continuity mistake: In the scene where Detective Lockely arrests Angel in the apartment, the window behind them shows that it's daytime. But when Angel jumps out the window, it's night time.
Continuity mistake: When Faith is sitting at the window and looks at the piece of broken glass she used to torture Wesley, it has a different shape than the one she first takes to torture Wesley. When she drops it out the window it has its original shape again. (00:33:10)
Disharmony - S2-E17
Continuity mistake: When Cordelia and Harmony are on the couch talking and drinking, the towel on Cordelia's head goes from on her shoulder to behind in the change from wide to close up. (00:10:30)
Continuity mistake: When Cordy throws the knife at the door after Willow leaves, the knife hits at an impossible angle from where it was supposed to have been thrown.
Continuity mistake: When Cordelia looks at the monitor, the reflection of Angelus's cage shows Angelus standing at the bars next to Connor. It cuts to a direct shot, and Angelus is sitting on the ground on the other side of the cage. (00:21:40)
Continuity mistake: In the season 5 episode 'Destiny' we see that the first time Angelus meets William, he has already adopted a more cockney accent, but in an earlier episode of BtVS (Fool For Love) Angelus asks Spike "Since when do you talk like that", suggesting he changed his accent after they met.
Continuity mistake: The entire area around Cordelia and Skip is supposed to be frozen in time. However, there is a car driving freely across a bridge in the background behind Cordelia. (The background is blurred, so it is difficult to see.)
Disharmony - S2-E17
Continuity mistake: In 'Disharmony' Willow's hair is over her eye when she says "Thanks for the affirmation", but when we see her again a second later its tucked behind her ear. The shot wasn't on Cordelia long enough for her to have tucked it back. (00:16:45)
Quickening - S3-E8
Continuity mistake: Sahjhan establishes that he is incorporeal on Earth, but when he takes Holtz to meet his demon minions, he manages to knock on the door.
Are You Now Or Have You Ever Been - S2-E2
Continuity mistake: When Angel hides the bag of money up on the shelf in the basement, he is not wearing glasses. However, in the close up shot of his arms and the bag though, he is.
Continuity mistake: After Cordelia kisses Connor, her hand is on his cheek. Just before she says "and if this is the end", in the shot of Connor she removes her hand, then the angle changes to show her, and her hand's suddenly back on his cheek again.
Continuity mistake: The girl being rescued at the beginning goes from standing close to the wall, looking blank in one shot, to being further away from it looking concerned in the next.
Inside Out - S4-E17
Continuity mistake: The sketch of Cordelia that Angel looks at depicts her facing to her left. But once he places it back on Wesley's desk, it depicts her facing to her right, revealing a flipped shot.
Answer: Due to his epiphany, Angel basically had the 'true darkness' he worked so hard to reattain ripped away from him, like his soul was after sleeping with Buffy.