Tranq gun

In the scene in Soulless where Wesley saves Fred by shooting Angelus with the tranquiliser gun, the stage directions were as follows:

Then, PPHHHHTT! A tranquilliser dart pierces Angelus’s shoulder. A flash of annoyance passes across his face. Then, woozy, he STAGGERS back releasing Fred.
REVEAL Wesley, halfway down the stairs, tranq gun still levelled as, PPHHHHTT! Wesley shoots another dart - this one into Angelus’s neck. Angelus goes slack and hits the ground with a THUD.

Svea Priestesses

The Svea Priestesses, also known as The Svear, were a powerful mystical order of women. Descendants of a powerful Nordic priestess called Svea, they attempted to banish the Beast, who turned to Angelus for help. When Angelus told the Angel Investigations team of his association with the Beast, they went to contact the Svea, only to discover that they had been slaughtered.

Indiana Jones

Warren calls Jonathan “Short Round” in Conversations with Dead People and Entropy. He was Indiana Jones’ partner, played by Jonathan Ke Quan, in Indiana Jones and the Temple of Doom. In All the Way, Zach says to Janice, “Pumpkins, very dangerous, you go first”. This is a reference to Raiders of the Lost Ark in which Indiana Jones sees snakes in his way. His friend Salla says “Asps, very dangerous, you go first”.
In Awakening, Angel says, “Wood. Why did it have to be wood?” after he sets off the booby trap. This is a paraphrase of Indiana Jones’s famous line “Snakes. Why did it have to be snakes?” from the 1981 film Raiders of the Lost Ark. Much of the action in Angel’s fantasy in Awakening is inspired by Indiana Jones movies. In Soulless, Angelus says to Wesley, “Here’s one for you. What’s the deal with Angel and Raiders of the Lost Ark?”

Oedipus Rex

At the end of The Puppet Show, Xander, Buffy and Willow nervously performed a piece from the Greek tragedy Oedipus Rex, written by the Greek playwright Sophocles (496-406 B.C.). Xander played Oedipus, Willow played the Priest of Zeus, and Buffy played Jocasta, Oedipus’ mother/wife.
Willow suddenly ran off the stage in fright - which was not part of the script. Alyson thought it seemed right that Willow would have stage fright. This fear was taken up by writers and showed in several future episodes, such as Nightmares.
In Soulless, Angel references the play to Connor when he says, “And now my boy’s in love… all hearts and flowers. But doesn’t it freak you out that she used to change your diapers? I mean, when you think about it, the first womanyou boned is the closest thing you’ve ever had to amother. Doing your mom and trying to kill your dad…hmm, there should be a play.”

Teddy Bear’s Picnic

At the beginning of Soulless, Angelus sings,

“If you go into the woods tonight,
You won’t believe your eyes.
If you go into the woods tonight,
You’re in for a big surprise…”

This is a paraphrase of the lyrics for the childrens’ song Teddy Bear’s Picnic, the lyrics of which are:

“If you go out in the woods today
You’re sure of a big surprise.
If you go out in the woods today
You’d better go in disguise.
For every bear that ever there was
Will gather there for certain, because
Today’s the day the teddy bears have their picnic.”

Seen at 21.42 minutes:

When Cordelia looks at the monitor at the scene in the basement in Soulless, we see Connor walking towards the left side of the cage (on the screen), but when the shots cuts to the basement, Connor’s position is completely different.