Sophie Zelmani’s “I’ll Remember You” plays when Buffy and Angel kiss goodbye in the episode Angel.

In Angel, Darla says, “Come on, Angel. Just say yes.” She’s paraphrasing the famous anti-drug message from the 1980s: “Just Say No”. It was first coined by Nancy Reagan, though British viewers may remember the kids from Grange Hill singing their version of the message.

In Angel, Buffy says about Giles’s training quarterstaff, “I’m not gonna be fighting Friar Tuck.” Friar Tuck is the well-known ‘holy’ man in the legend of Robin Hood.

In the episode Angel, the Master says, “out of the mouths of babes”, which is from Psalms 8:2.

We discover a lot about vampires in the first season episode Angel. Only direct sunlight seems to kill vampires in the Buffyverse as both Darla and Angel are able to stand in filtered sunlight. We also discover in that episode that bullets can’t kill vampires.
The belief that a vampire …

In Angel, we see that the Master has begun training the Anointed One, who arrived in Sunnydale in Never Kill a Boy on the First Date.

In the episode Angel, Angel says to Darla, “What’s with the Catholic schoolgirl look? Last time I saw you it was kimonos.” This line was followed up four years later in the Angel episode ‘Darla’. In a flashback to the Chinese Boxer Rebellion, Darla wears a kimono.

When Angel hears Joyce scream in the episode Angel, it’s actually a reused version of Buffy’s scream taken from earlier in the episode.

The Anointed One was a small boy named Colin who became a member of the Master’s Order of Aurelius. Buffy believed she had killed The Anointed One in Never Kill a Boy on the First Date but she got the wrong vampire. The Anointed One led Buffy to the Master …

In Faith’s dream, as Faith drags herself out of the grave, the rain doesn’t appear to be actually hitting her. It looks like they just made Eliza Dushku wet, and then added computer generated rain, to avoid the difficulties of filming a close up rain scene.

Buffy throws Faith across the dining table as they fight, knocking everything off the table. A few moments later, the tablecloth and some pieces of fruit are back on the table.

When Buffy and Faith are rolling down the stairs, you can see a camera following them to the left.

When Faith is rummaging through Joyce’s make-up, you can’t see her trademark tattoo on her arm.

Tara’s pendant around her neck moves without her touching it when she and Willow look for Faith.

Whilst running away from Buffy, Faith climbs a wall. The wall wobbles around giving away that it’s a fake.