In several long shots of the Beast, you can see he has normal feet rather than the cloven hooves shown in the closer shots.
When rain falls buildings get wet, so when a rain of fire falls it seems that buildings should be getting burned.
Angel: (Talking about weapons) Still, good to know what you're using. I mean, what if I'm fighting a glurgh and I ask for a khopesh to finish him off, what would you throw me?
Lorne: Uh, a towel? Glurghs are ninety percent pus.
Lorne: No, I don't think that much mucus is ever a good sign. Uh huh. Oh please, please, yeah, describe it in detail.
Gunn: Okay, what's the plan?
Angel: You're holding it. We figure out what all this means, then do something large and violent.
Wesley: I see you've given this considerable thought.
Lorne: Well, it might take a couple of days, you're fifth on the bleeding walls list. Spritz a little 409; we'll get back to you.
Angel: He's right, you should probably get some sleep.
Cordelia: Yeah, because impending doom, almost as good as warm milk.
Lilah: Couldn't you have at least tortured (Gavin) a little bit more?
Angel: Really wanted to, but he wouldn't stop talking long enough for me to get into it.
Gunn: Well, if Snowball hasn't tried to eat your spine yet, hit her with the catnip till we get there.
Lorne: Do we fight snakes?
Angel: Only if they're giant, or demons, or giant demons. Are they giant demon snakes?
Wesley: Why are you dressed like that?
Lilah: (imitating Fred) Isn't this what you like? Big brain and a tight little…
Lilah: Forget that evil witch. Let's talk about me. I'm good and I'm pure and science turns me on, and one day, if I pray hard enough and eat all my vegetables, I just might have hips.
Angel: Maybe we can help each other. The enemy of my enemy...
Lilah: Can kiss my ass.
Joss Whedon states in the Season 5 DVD featurette "To Live and Die in L.A.: The Best of Angel", that this episode is one of the best episodes of Season 4 and of the series as a whole.
Andy Hallett (Lorne) is credited as "Special Guest Star Andy Hallett."
There was some confusion about the title of this episode because the WB ran promotions for it which used the tagline "Rain of Fire." Many thought this was the title until it became public knowledge that the actual title was "Apocolypse, Nowish," and some then believed that the WB had used a different title due to legal problems with the movie allusion. Actually, studio promo spots almost never use the title of the episode, and this was just a case of finding a tagline that sounded catchy and described the episode. If there were legal problems, the actual title would have been changed as well.
Charisma Carpenter looked visibly pregnant in the scenes with Connor, as she paced the floor.
Although Daniel Dae Kim has an up-front guest listing, he has no dialogue and barely moves during his appearance in this episode.
The Beast is the one Cordelia saw at the end of 'Spin The Bottle' (4x06) just before she ran to her room after she got her memory back.
Gunn: You had me at "fire."
This line is reminiscent of Renee Zellweger's popular line in Jerry Maguire: "You had me at 'hello.'"
Lorne: I'd hate to be the the demon that cried Apocalypse, Nowish but...
The title of this episode and the above quote comes from the movie Apocalypse Now.
Lorne: I'm gonna need a bigger arrow.
When the gang confronts the Beast on the roof, Lorne says almost the same thing that Brody says in Jaws when he gets his first look at the shark: "You're gonna need a bigger boat."