Revealing mistake: At the very beginning of the episode, Lyle's reflection can be seen in the tiles on the floor in the shopping mall.
Other mistake: When Buffy and Angel escape from Spike, Dru and the Judge they jump down into the sewer, then run all of five metres before going up the ladder to escape. When they come out of the sewer they are in a very open area with the factory nowhere in sight. They have not travelled far enough for this to be the case. (00:39:15)
Continuity mistake: Near the beginning when Buffy and Willow are talking about Willow getting together with Oz, Buffy's hair is in front of her ears. Then she turns to face Willow to say, "You think he's too old 'cause he's a senior? My boyfriend had a bicentennial," and in that shot change, her hair switches to behind her ear then goes back to being in front of her ears in the next shot without her every touching her hair.
Character mistake: In this episode, Buffy says that Drusilla could be alive because they 'never saw her body'. Drusilla is a vampire; if she was dead, there wouldn't be a body to see - as the slayer, Buffy knows this.
Continuity mistake: When Buffy wakes up she is wearing metallic nail polish, yet when she went to sleep previously, she has no nail polish on. Later in a scene where Buffy is dreaming about her night with Angel she has the nail polish on again, even though that took place the night before when she did not have her nails painted. (00:01:15)
Continuity mistake: In Innocence, when the Scoobies are in the library, Oz (I think) says for the crew to meet outside Xander's house a half hour later. Then we cut to Buffy strolling through Sunnydale High in broad daylight, then back to Oz's van outside the military base and it's last night again. (00:23:15 - 00:29:20)
Other mistake: When Angel, Drusilla and The Judge enter the mall, The Judge kills a pedestrian as he tries to get away. But no other pedestrians that are in the mall notice - A big blue guy just set a man on fire and disintegrated him into tiny pieces in a public mall and NOBODY noticed?
Continuity mistake: The book that Cordelia replaced sideways in the bookshelf behind her disappears, and then reappears just before she and Xander kiss.
Revealing mistake: In the scene where Drusilla and the new reformed Angelus are in the shopping mall and they got blown over the side after Buffy fires the grenade launcher at the Judge, you can tell that it was Mike Mass and not David Boreanaz that got blown over the side.
Continuity mistake: When Willow catches Xander and Cordelia kissing in the library, the hair next to Willow's right ear moves between shots as her and Xander are talking in the hallway.
Continuity mistake: When the Judge is blown up, Drusilla and Angel leap from the balcony. In mid-air, they somersault and their backs are facing the ground as they fall, but a second later they land on their stomachs.
Revealing mistake: Drusilla's reflection can be seen in the metal part of what appears to be the base of a shopping mall map just as she's getting up after the Judge has been blown up.
Continuity mistake: When Buffy is told that Angel has become Angelus, she mentions "I should have known. When I saw him at the house he was different", but her earlier conversation with him took place not at the house but at his apartment. This isn't just a strange turn of phrase - the scene was originally shot at the Summers house, but was changed to Angel's apartment for more emotional resonance.
Plot hole: After losing his soul, Angelus kills Jenny Calender's uncle, who is a descendant of the gypsy clan who cursed him. But, since there is nothing to suggest the uncle's room is in a public location, Angelus couldn't have gotten in the room without an invitation.
Visible crew/equipment: Right after Kane and Buffy's fight in the woods, in the shot right after Kane leaves, you can see set-lights above the clearing where they fought. (00:39:10)
Chosen answer: Angel is saying that he is still jealous and Buffy recognizes that this is his way of saying he wishes that they could be together. That is why they both smile.