This is the first time it is revealed that Niles gets nosebleeds when he violates his ethics. It would be a plot point in later shows, such as the episode "Kisses Sweeter Than Wine".
Life at KACL Frasier gives a time check of 4:25 in this episode, which indicates that he has a coveted "drive time" slot at KACL, probably 2-5 or, less likely 3-6. This ties in with other hints, such as the late afternoon, pre-dinner coffees at Nervosa.
When Frasier and Catherine are fighting towards the end of the episode, Catherine's blouse changes from being open to closed, and back again, from shot to shot.
(Martin and Daphne are singing Deck the Halls)
Frasier: Excuse me, excuse me. Exactly how long have I been asleep.
Daphne: My grandfather used to nap every afternoon. He lived to be 93.
Daphne: He'd lie there on the sofa and you couldn't wake him for the world. Grammy would say: "He might as well be a dead man." Then, of course, one day we couldn't wake him. He really was a dead man. Poor Grammy. For weeks, she kept insisting: "He's napping, he's napping."
Niles: As long as your conscience is clear. I'm not sure mine would be.
Frasier: Well frankly I don't care about your concience. And I don't need your approval, and I don't need you to like it, in fact I don't need you for anything. Oh by the way Niles, my car is in the shop, I need you to give me a ride home tonight.
Niles: No problem.
(Upset at not being able to make love to Catherine)
Frasier: This is killing me! You think I don't want to pick you up right now, carry you over to that Eames classic and show you why it's the best-engineered chair in the world?!
Frasier: Every time we touch and kiss I get queasy.
Catherine: (Incredulous) What are you telling me? That the thought of making love to me makes you sick to your stomach?
Frasier: Yes, but don't take it personally!
Catherine: (angry) And to think I was going to have sex with you. And it was going to be hot. Oh, like you've never had before. I'm talking raw, steamy, sweat-dripping-down-your-back, neighbors-pounding-on-the-wall, ILLEGAL-IN-FORTY-EIGHT-STATES-KIND-OF-SEX! (haughty) But, hey! You're okay, you won't be alone tonight. No, you've got your ethics! (pause) Oh, by the way...the fish was dry.
Frasier: Oh, that was a cheap shot!
Roz: (bitter) I've seen the future, and its name is Marco.
Frasier: What do you think, Seattle? Are there any non-Marco's out there? Or is Roz here destined to live a life of hopeless, loveless, spinsterhood. Back after this.
Roz: (sarcastic) Gee, I just love it when you include me in your show.
Frasier: (depressed) How I envy you, Eddie. The biggest questions you face are "Who's going to walk me?" "Who's going to feed me?" I won't know that kind of joy for another forty years.
United Kingdom: 1st June 1994, Channel 4
Title Card: "Twas two months before Christmas..."
This is a play on the opening line of the famous holiday story, The Night before Christmas.
Scene Six Title: HE'S BAAACK
This is a variation of the tagline "They're back" from the 1986 film Poltergeist II: The Other Side, sequel to the 1982 film Poltergeist in which the tagline was "They're here".
Scene Three Title: M&M'S AND SYMPATHY
This is a variation on the title of the Robert Anderson play and 1956 movie Tea and Sympathy.