When Angel is asking the Oracles to bring Doyle back in Parting Gifts, he reminds them that they changed time in I Will Remember You:
Male Oracle: “You try our patience. What is done…”
Angel: “…cannot be undone, you keep saying that. But I need Doyle. You …

The Ramsey Hotel scenes in Parting Gifts were actually shot at The Ambassador Hotel in los Angeles.

The hotel was a landmark in the city and the site of many Academy Awards ceremonies. The hotel and it’s nightclub, the Cocoanut Grove, were favoured by many Hollywood stars including Marilyn …

Cordelia says in Hero, “He’s a larger than life character, way too Braveheart for Joe Couch Potato to relate to.” This is a reference to Mel Gibson’s film about William Wallace.

The pier that was used for the scenes with the ship in Hero was at Southwest Marine, in Sanpedro/Long Beach, the Port of Long Beach.

Brachen demons have red eyes, spiked greenish skin, and are very strong. They are also reputed to have a good sense of direction. One of the clans lived in Oregon woods for a time. Doyle’s father, whom he never met, was a Brachen demon, making Doyle part-demon too.

The following conversation was cut from the Angel episode I Will Remember You. It references the Buffy episodes Surprise, Innocence, Becoming (Part 2), Faith, Hope and Trick and Graduation Day (Part 2):

Doyle: “So Buffy and Angel? It’s always been pretty volatile?”
Cordelia: “That was nothing. One time they kicked …

In I Will Remember You, Doyle says “Orson, we’re in a situation here!” This is a reference to the TV show Mork and Mindy, starring Robin Williams, in which Mork reported to his leader Orson.

We see in I Will Remember You that the Book of Kelsor says Mohra demons are assassins who take out warriors on the side of good. They need vast quantities of salt to live and their “veins run with the blood of eternity”. If they’re killed, they regenerate …

In I Will Remember You, Buffy says to Angel, “What is it? You can see me, but I can’t see you? What are we playing here?” This is similar to what Giles says to Angel in Pangs when he tells him, “It’s not fair. You know that’s what she’d …

When Buffy first arrives at Angel’s office, just after she says, “a little upset”, you can see Angel’s reflection in the office door behind her.

The cross that Doyle is wearing round his neck in The Bachelor Party jumps from being inside his vest to being outside between shots when he is talking to Harry.

We find out a lot more about Doyle’s history in the episode The Bachelor Party. He used to teach third grade kids, and helped out in soup kitchens, where he met his wife Harriet. They were madly in love but separated when he discovered he was part demon aged …

When Kate catches up with Spivey in Sense and Sensitivity, he throws a bag on top of his car. In the next shot it has gone, but then appears again in another shot.

A second assistant director on Angel named Robert Papazian Jr was probably the influence for the name of the character Little Tony Papazian in Sense and Sensitivity.

Both Angel and Buffy paraphrase the sentence “Light at the end of the tunnel”:
In Hell’s Bells, whilst tying Xander’s tie, Buffy says, “You and Anya give me hope. It’s like… you two are proof that there’s light at the end of this very long, long, nasty tunnel.” Then, when Xander …