Continuity mistake: When Lorne covertly warns Angel that the hotel is bugged, he places a note in Angel's pocket with his hand on Angel's shoulder. When Wolfram and Hart watch the video feed later, the hand that was on Angel's shoulder is now in front of Angel's chest. (00:22:50 - 00:37:00)
Plot hole: When Angel is being pursued by the Lilliad demons, he is holding his son Connor and is talking to him in the car. Later on it is revealed that he is in fact holding a teddy bear with a bomb attached to it. If it wasn't his son, why was he talking to it? It couldn't be to fool the Lilliad demons because they wouldn't be able to hear him, as they were in separate vehicles.
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.