Other mistake: In the episode "The Shroud Of Rahmon," when Angel changes into his vampire face, his teeth don't change into fangs. (00:33:55)
Disharmony - S2-E17
Other mistake: When Harmony spills her pig's blood on the keyboard, the computer shorts out, and the monitor flickers off, but the mouse cursor is still visible. (00:25:35)
Disharmony - S2-E17
Other mistake: At the very end, as Angel walks out the door he reflects in the panes of glass on the door. (00:42:10)
Other mistake: Both times we see Lindsey shaving, once before his hand transplant and once after, his reflection in the bathroom mirror isn't in fact a reflection. He is wearing a bracelet on his left wrist, but in the mirror it is on his right wrist.
Other mistake: Later in the day when Cordy has recovered a little and is cleaning, Angel says something about seeing a reflection in the picture. We hear Cordy say, "What do you want," but the subtitles say, "What do you what?"
Answer: Everybody including Angel saw her. After helping them and then being left alone to talk to Angel, Cordelia says that the Powers That Be let her come back one more time to help them. After Angel gets a call saying that she died, he realises that it was her spirit that was helping them the entire time.