During one of his feverish dreams in Soul Purpose, Fred says to Angel, “Nothing. I can’t seem to find anything wrong with you. I mean… except that you’re empty. There’s nothing left. Just a shell.” A few episodes later Fred is infected by Illyria and becomes just that - a …

In Harm’s Way, Tamika comments that Harmony’s desk (and thermos) are covered with unicorns. We know that she loves the mythical animals from the Buffy episode Real Me.

In Harm’s Way, Harmony mentions that she was vamped during her high school graduation - seen in Buffy’s Graduation Day (Part 2).

The song that plays as Harmony wakes up in Harm’s Way is “Hey Sailor” by Detroit Cobras.

When the lights suddenly go out in Lineage, Spike shouts, “You’ll never take me to Hell, Pavayne!” This is a reference to the episode Hell Bound, in which the ghost of Pavayne was trying to send Spike into Hell. Spike is clearly still frightened by the experience.

In Spin the Bottle, a regressed Wesley prodly tells the others, “I am from the Watcher’s Academy in southern Hampshire. In fact, I happen to be head boy.” In Lineage, Wesley’s father says of his son, “Oh, the academy didn’t make him head boy for nothing. Mind you, as I …

In Lineage, Wesley’s father says of Angel, “He’s a puppet. He always has been. To the Powers That Be, to Wolfram & Hart. Now he’s ours.” In Smile Time, Angel literally becomes a puppet.

In Unleashed, Royce uses Calendula to block Lorne from reading him whilst singing. Calendula is in fact a flower with yellow or orange flowers - related to the Marigold. In medicine, it has properties that reduce inflammation, control bleeding and soothe irritated tissue.

In Unleashed, Fred says of Angel, “Girls, guys… puppies. He’s pretty much an equal-opportunity saver.” This could be a reference to the episode Orpheus, when Faith witnessed Angel’s past life - including saving a puppy.

David Boreanaz is a hockey fan - he even took part in a celebrity game when the NHL All-Star game was held in Los Angeles. In Loyalty, Angel buys Connor a mini hockey shirt and sticks, and he can be seen watching a game in Life of the Party.

In The Cautionary Tale of Numero Cinco, Spike says to Angel, “If wishes were horses…” In Not Fade Away, after Illyria says, “I wish to do more violence”, Spike says, “Well, wishes just happen to be horses today”.

Both Carey Cannon and Randall Slavin, who played the Oracles in Angel had auditioned for roles on Buffy before. In an interview with Buffy Magazine, they said:

Carey Cannon: “I actually had met casting director Amy Britt when I auditioned for another role on Buffy, so when this role on Angel …

Knox worked in the Wolfram & Hart science lab under Fred’s management. A geeky but seemingly non-evil type, he had a crush on Fred, who (eventually) made it clear that she has no romantic intentions towards him. He was a devoted follower of Illyria, one of the old ones, …

Lush have a beauty product called Buffy the Backside Slayer for sale. It contains “a combination of ground grains to exfoliate your legs and backside which give you a right good scrubbing, plus wonderfully smoothing oils and stimulating fragrances.”

In “I Robot, You Jane,” Buffy makes a big deal out of how her hair looks after she was electrocuted. She then goes to the computer lab and discovers Dave’s body, but when she comes back, her hair’s back to normal. Surely she didn’t stop to brush it in the …