In Lullaby, Lilah says, “Harvey? It’s Lilah. I got a job for you… Angel Investigations. Yeah, full cleaner service.” This could be a reference to two ‘cleaner’ characters played by Harvey Keitel in the movies Pulp Fiction and Point of No Return.

In Quickening, Cordelia says, “Nothing a couple of Band-Aids and a pint of Heath Bar Crunch can’t fix” referring to the popular brand of US bandages and one of the many flavours of Ben & Jerry’s ice cream.

In Welcome to the Hellmouth, Willow reveals to Buffy that she and Xander broke up after he stole her Barbie, referring to the bosomy Mattel doll. In Offspring, Lorne says, “This is way beyond my ken - and my Barbie, and all my action figures.”

In Offspring, Fred tells Angel about a Pylean word which reminds her of his and Cordelia’s relationship:

Fred: “Kyrumption. It’s the one nice word I remember from the Pylean hell dimension.”
Angel: “What’s it mean?”
Fred: “It’s when two great heroes meet on the field of battle and recognize their mutual fate. …

When Billy goes to his cousin’s apartment in Billy, we hear “Clint Eastwood” by The Gorillaz.

In Fredless, Fred’s father and Angel have the following conversation:

Roger: “Now, Spiro Agnew, I know he was…”
Angel: “A Grathnar demon! You knew that? I thought I was the only one that knew that!”
Roger: “What else would he be, but a demon?”

Spiro Agnew was the thirty-ninth Vice President of the United …

According to Jane Espenson’s DVD commentary for the episode Superstar, Buffy is supposed to say “I’m just kidding!” over the credits at the end of the episode. Espenson probably wrote the line in the script but it was cut later and she didn’t realize it.

In Fredless, Roger Burkle and Angel have the following dialogue:

Roger: “Well, I tell ya, I hadn’t seen a stroke like that since Nicklaus took on Gary Player in the ‘63…”
Angel and Roger in unison: “Bob Hope Desert Classic.”

They’re talking about a PGA Tour golf tournament which is played each January …

In Fredless, Wesley, Gunn and Angel are carrying out an inventory of the weapons cabinet, as Cordelia had moved some “dust-catchers” down to the basement in Angel’s absence, seen in Heartthrob. Cordelia: “No. Angel - keeps complaining that the weapons cabinet is all different.”

For some unexplained reason, Wesley has a framed photograph of British war-time Prime Minister Winston Churchill behind his desk in the Hyperion Hotel. This can be seen clearly in Fredless.

In Hush, the whole of Sunnydale has gone silent. Joyce Summers is in Sunnydale. Why is it that Buffy doesn’t even once wonder how her mother is? The Gentlemen might have taken her heart when Buffy wasn’t there!

In The Wish, Vamp Willow gets a weapon from a cupboard to torture Angel with, but the scars on his chest are all burns. She and Vamp Xander then use matches to torture him. Why did she need the weapon?

In The Witch, Amy in her mother’s body is eating something when Giles and Buffy turn up at her house. When she puts it down, we hear a packet rustle. When we see a shot of the food a bit later, there is no packet, and the brownies …

Phlebotnum, a term coined by David Greenwalt according to Joss Whedon’s commentary for The Harvest, means any magical or mystical force or event that arises in the process of inventing the Buffy mythology/ or advancing the plot. Joss mentions phlebotnum in the commentary for Chosen, and David Greenwalt discusses it …

In Prophecy Girl, Buffy is bitten by the Master before he opens the Hellmouth. Later, when she is revived, we see a few shots that show the side of her neck that got bitten, but there is no sign of a bite, and it doesn’t seem to hurt.