Guy: (To Niles who he thinks might be gay, like himself) Annie is not your... cup of tea?
Niles: (Placing his hand on Guy's knee) Just between us, my interests lie elsewhere this weekend (Winks).
Guy: (Leeringly) Oh, really.
After Guy says "Oh, really", the shot changes to catch Niles' reaction. If you look at Guy, however, you can see it is simply another perspective of him saying "Oh, really", but without sound. The editor has simply used the shot again for Niles' reaction.
Niles states that while they were courting, he sent Maris a valentine stating:
You are the girl my heart adores, Everything I have is yours.
Now his lawyers are calling it a prenup. However, as we are all aware, Niles has stated (on more than one occasion) that there IS a prenup in place. (Take Season 4's "Are You Being Served?", for example).
Even though Maris might prefer to use the old valentine as a prenup, the laws of any state would preclude this because the prenup was clearly executed after the valentine. This means even if the valentine was deemed a valid prenup (which is unlikely), the existence of a later instrument that is final and complete (the actual prenup) would invalidate and override the earlier instrument.
Guy: (after Frasier barges into his room, dressed only in a towel) You're not the Crane I want!
Frasier: You're not even the sex I want!
Guy: Where is Niles?
Frasier: Oh, Niles!
Niles: Frasier! What are you doing in Guy's room?
Guy: Don't be jealous, Niles, it's not how it looks.
Niles: Oh. (turns back, then realises what Guy just said) What?!
Frasier: You know, Roz, maybe it's time you set some limits. Good lord, how hard can it be to say 'no' just once...? Oh well, look who I'm talking to.
Frasier: Look at that vista, it's stunning! Puts one in mind of the Matterhorn, doesn't it?
Annie: Oh, I wouldn't know. I'm not very musical.
Frasier: You speak French as well?
Annie: No, all I know how to say is 'oui'.
Frasier: Well, that should be enough to get you through the weekend.
(Frasier and Niles are discussing Daphne's friend Annie who has come along on a ski weekend)
Niles: I grant you she's comely, but don't you find she's a tad--what would the polite euphemism be---stupid?
Frasier: Niles, she is just unschooled, like Liza Doolittle. You find her the right Henry Higgins, she'll be ready for a ball in no time.
Niles: Leave it to you to put the "Pig" back in "Pygmalion."
Scene Four Title: COULD GUY'S LAST NAME BE FEYDEAU?
This references Georges Feydeau (1862-1921), a French playwright who specialized in farces of this episode's type.