David Nabbit was supposed to become a recurring character in Angel, but this didn’t work out due to scheduling. He appears in War Zone, To Shanshu In L.A., and in the season two episode First Impressions.

I swear there’s a visual reference to the movie Grease in the episode Flooded.
Towards the end of the episode, when Buffy steps out onto her back porch a lit cigarette butt lands at her feet, and she immediately knows who flicked it. Buffy extinguishes it with her (stylish yet …

In Flooded, Anya says to Xander, “don’t be such a wienerdog”, trying to persuade him to make an announcement about their engagement. This is a reference to the Todd Solondz film Welcome to the Dollhouse, in which the main character is cruelly taunted with the name ‘weinerdog’ by all the …

When we see Cordy drink Angel’s blood suppy in Expecting, she drips blood down the front of herself but later, when see her hit Wesley with the book, there is no blood there.

The Haxil Beast (latin name: ‘Haxil Daemonica’) offers wealth, fame and success to human men to impregnat human women with it’s spawn. It then telepathically controls the women via it’s link to it’s unborn children. The gestation period is very short and the women give birth very quickly. …

This stage direction is from the script for Expecting, in the scene in which Angel and Wesley get the wrong house whilst demon-hunting:

Wesley charges in, startling an ELDERLY COUPLE watching TV. Angel charges in behind him, SMACK! right into the ‘No Uninvited Vampires Allowed’ threshold.

Both Cordelia and Wesley have drunk blood on Angel - Cordelia drinks Angel’s blood supply from his fridge in Expecting and Wesley is offered blood when pretending to be Angel in Guise Will Be Guise.

Jeremy Renner, who played the vampire Penn in Somnamulist, has also been in A Little Trip to Heaven, North Country, Lords of Dogtown, S.W.A.T., Monkey Love, CSI: Crime Scene Investigation, Fish in a Barrel, Time of Your Life, The Net and Zoe, Duncan, Jack & Jane.

When discussing Penn’s murders, Cordelia and Wesley have the following exchange in Somnambulist:

Cordelia: “No lie. Gallagher’s changed his act more times than this dude has in the last two centuries. Why do you figure he’s still doing the same old schtick?”
Wesley: “Well, I mean it’s a classic, isn’t …

When Cordelia tries to persuade Angel to take a license plate to Kate in Somnabulist, the following line cut due to length:
“Just remind her that if it wasn’t for you she’d be the curdled gooey leftovers of a proto-Babylonian Burrower demon. Or words to that effect. You’ll pretty …

We discover in Somnabulist that vampires who are linked by blood (such as a sire) can sense each other’s presence and can be physically linked in dreams. This occured when Angel began to dream about the murders commited by the vampire he sired, Penn.

In Somnabulist, the following conversation occurs:

Angel: “Got held up in Romania.”
Penn: “Romania. What’s in Romania?”
Angel: “Gypsies.”

This is a reference to the Buffy episode Becoming (Part 1), in which we see gypsies give Angel his soul back.

Kungai demons, one of which is seen in Parting Gifts, are a powerful race of yellowy-green, Asian demons whose Tak horns suck the life force out of an enemy. They are relentless killers but die when their horn is removed.

When the mysterious demon hunter in Parting Gifts touches the demon blood at the side of the building, the hand belongs to a black person. We later find out that the demon hunter on the bike is actually Wesley… who is white.

In Parting Gifts, Barney says, “I don’t think he’s tracking me down to tell me I won Publisher’s Clearing House.” This is a reference to the multimillion dollar prize made famous by Ed McMahon.