Ground State - S4-E2
Factual error: In the flashback to Gwen as a child in 1985, she is dressed in a jacket tagged with an "Old Navy" zipper. That clothing store chain wasn't founded until 1994.

Ground State - S4-E2
Factual error: In the flashback to Gwen as a child in 1985, she is dressed in a jacket tagged with an "Old Navy" zipper. That clothing store chain wasn't founded until 1994.
Continuity mistake: After Wesley, Cordelia and Gunn sing "We Are The Champions" and Cordelia mentions tequila being evil, we see Wesley put aside some shot glasses. These glasses change position three times throughout the rest of the scene without anybody touching them.
Cordelia: You want I should distract him? Make with the nice-nice while you slip by?
Angel: Don't be stupid. I'm that guy and the most beautiful woman I've ever seen is making eyes at me? It's either a bachelor party or a scam.
Cordelia: What did you just call me?
Angel: I'm sorry. You're not stupid.
Cordelia: No, after that.
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.