Karen: Tell me, what would you do in my position?
Harry: What position is that?
Karen: Imagine your husband bought a gold necklace and come Christmas gave it to somebody else...
Harry: Oh, Karen...
Karen: Would you wait around to find out if it's just a necklace, or if it's sex and a necklace, or if worst of all it's a necklace and love? Would you stay, knowing life would always be a little bit worse? Or would you cut and run?
Harry: Oh, God. I am so in the wrong. The classic fool.
Karen: Yes, but you've also made a fool out of me, and you've made the life I lead foolish too.
When Mark is watching Billy on TV, prior to Juliet arriving, in one shot behind him you can see a long wooden pole leaning against the wall to the right. This disappears in the next shot.
Any viewers outside of Britain might not get the joke when Billy Mack isn't sure which one is Ant or Dec. They are very well known in the UK, and dominate Saturday night telly. The joke refers to the fact that even though they are popular, a lot of people don't know which one's which.