Heartthrob - S3-E1
Continuity mistake: In the scene where Angel has just returned and given Cordelia her necklace, watch Cordelia's hands; they keep changing position in each shot. In one shot she is trying to put the necklace on, in the next shot she appears to have given up and brings her hands down and bundles the necklace in her hand. Then when the shot changes to behind her, she is trying to fasten the necklace behind her neck again. This happens a few times during this scene.
Heartthrob - S3-E1
Revealing mistake: When James, a vampire, chases Angel and Cordelia into the subway, James' reflection is visible in the windows of a passing train.
Heartthrob - S3-E1
Revealing mistake: In this episode both Angel's and James' reflections are visible during the fight scene inside the train.
Heartthrob - S3-E1
Character mistake: In the first flashback to Angelus and James in Marseille, Angelus briefly speaks with his modern-day American accent before reverting to his Irish accent.
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.