In the Angel season four episode ‘Deep Down‘, Angel says the following line to his son, Connor:

“What you did to me - was unbelievable, Connor. But then I got stuck in a hell dimension by my girlfriend one time for a hundred years, so three months under the ocean actually …

In the Angel episode ‘Waiting In The Wings’, Angel and Cordelia are taken over by the spirits of old lovers. In the episode Angel says: “Look, I’ve been possessed by the spirits of old lovers before. Never goes well.” This is a reference to the Buffy episode I Only Have …

Alyson Hannigan told Entertainment Weekly which her favourite Buffy episodes were in an interview in October 2005:

Hush: “It was a whole new way of figuring out how to act, the not-talking thing.”

The Body: “I just remember the no sound, no music - it was so disconcerting.”

Ted: “John Ritter was the …

At 4:54 into the episode, Buffy tells her mom it is 4:23. a minute and a half later (6:35) she says it was 4:24- however because it is a minute and a half later it should be 4:25.

This isn’t so much “trivia” as it is an observation, and a request for comment: Have any of you noticed that in the entire seven season DVD set of the show, neither Sarah Michelle Gellar not Allyson Hannigan contribued in the form of an episode commentary or in any …

In Get It Done, Andrew greets Buffy and Wood by saying that the funnel cake he’s been making has been kicking his ass. Buffy introduces Andrew as a hostage who bakes. Funnel cake his made by dripping batter out of a funnel into hot oil to fry it …

The reason for the amount of shoe “goofs” in Buffy the Vampire Slayer could be simply because of practical issues. When actor’s feet can not be seen/are out of shot, they often wear slippers or flat shoes so that they can be a bit more comfortable during the long shooting …

In Get It Done, the heels of Buffy’s boots change. Just before she leaps into the portal she is wearing stilletto-style boots (best seen when she first walks towwards the portal), but when she lands on the other side the heels are flatter and blockier.

In the Angel season two episode ‘Untouched‘, Bethany, the telekenetic girl stabs Angel through the torso with a bar. When he gets back to the hotel the following lines are said.

Angel: “You know how hard it is to think straight with a re-bar through your torso?”
Cordelia: “Actually, I …

At the beginning of Something Blue, Riley is helping some girls put up a sign in the University which reads “Lesbian Alliance.” This must be an effort to allude to the coming of Amber Benson and the ensuing Willow/Tara storyline in the next episode - Hush.

In the Angel season one episode ‘Blind Date‘, Cordelia calls Willow to get some help decrypting discs that Angel stole from Wolfram & Hart:

Cordelia: “Okay, I’m back to the desktop, Willow. What do I do now? Okay, done that. Back to life list. Yeah. Yeah.”
Wesley: …

The Buffy episode Fool For Love and the Angel episode ‘Darla’ aired in the same week in US. Both shows covered the 1880 turning of William to Spike, and how it affected Angelus.
In the Buffy episode, William is seen walking down the street with his poetry pages, where …

In Gingerbread, when the gang is looking at the computer in the library for articles on the “dead” children, the name of the writer of one of the newspaper articles is shown as C Meyer. This is probably a reference to the show’s set designer Carey Meyer.

Once More, With Hobbits is a rewrite of the lyrics of the songs from the Buffy musical episode Once More, With Feeling, to suit the characters and storylines from Lord Of The Rings. Songs include ‘I’ve Got a Theory’ sung at the council of Elrond and ‘Where Do We Go …

A few flashback scenes from Buffy the Vampire Slayer are seen in the opening episode of Angel - ‘City Of…‘ - whilst Doyle is telling Angel the story of his life:

Doyle: “Once upon a time there was a vampire. And he was the meanest vampire in all the land.” …