Doyle’s place

Doyle’s apartment is described in the script for ‘In the Dark‘ as:

It is, almost literally, the bachelor pad from Hell. Piles of laundry, crushed beer cans, and take out food cartons lie scattered about, mixed in with some super-natural knick knacks: a goats skull, black candles, books.

Howler monkeys

This line describing the sadistic Marcus in ‘In the Dark‘ was cut from the episode:

“Marcus was run out of Novi Grad by a pack of angry Howler demons for his antics with some local sprites - and you know Howler demons, they’ll hook up with anything.”

Living gargoyle

Spike’s first appearance in the script for ‘In the Dark‘ is described in the stage directions as:

Now we see who this narrator is: it’s SPIKE. Perched high overhead ona rooftop ledge, looking down on the alley like some living gargoyle. Having the time of his life.

Marcus’s torture chest

Doug Petrie included the following line in the script’s stage directions, describing Marcus’ torture paraphernelia in ‘In the Dark:

Marcus opens a battered old trunk filled with torture implements - among them we see a cat’s paw, a breast ripper, a heretic’s fork, “the pear”, etc.

Bruce Seth Green

Bruce Seth Green directed several episodes in seasons one and two. He also directed the Angel episodes ‘In the Dark‘, ‘The Prodigal‘ and ‘The Trial‘. Bruce is not a relation to Seth Green, despite their very similar names. Bruce has worked on Airwolf, Knight Rider, MacGyver, Xena: Warrior Princess, Hercules: The Legendary Journeys, American Gothic, Gilmore Girls and V.

Doug Petrie

Doug Petrie was a co-executive producer, writer and director on Buffy. He also wrote the Angel episodes ‘The Trial‘ and ‘In the Dark‘. Doug is a huge fan of comics. He’s written several Buffy comics and worked on the screenplay for the upcoming Fantastic Four feature film. There are loads of comic book references in Doug’s episodes. He has also worked on Tru Calling, Harriet the Spy and Clarissa Explains it All.

Kevin West

Kevin West played the sadistic vampire Marcus in In the Dark. He won a Best Actor Clio Award in 1989 for his performance in a Little Caesar’s Pizza advert entitled “Origami”. Since appearing in Angel, Kevin has been in Phil of the Future, The West Wing, ER, The O.C., Alias, Black Scorpion, Four Dogs Playing Poker and Gone in Sixty Seconds.

Marcus

Marcus was a vampire seen in In the Dark. He was hired by Spike to torture Angel for the Gem of Amarrah, but took the ring for himself and went in search of his obsession - children. Marcus was killed by Angel, who took the Gem and destroyed it.

Amarrah crossover

At some point between Graduation Day (Part 2) and The Harsh Light of Day, the gang (except for Xander) have found out that Angel was in L.A. Buffy gives the Gem of Amarrah to Oz to take to her ex-boyfriend. We see their adventures in the Angel episode ‘In the Dark‘, which features both Oz and Spike.

Arm in a box

Cordelia references Buffy episodes Surprise and Innocence when she tells Doyle about Spike in ‘In the Dark‘:

“Oh, and this one time he and Dru raised this demon that burned people from the inside. It was this whole weird thing with an arm in a box.”

Call in the decorator

In ‘In the Dark‘, Cordelia and Doyle have the following conversation:

Cordelia: “Please. I couldn’t get comfortable in here if the floor was lined with mink. I mean, how can you live like this?”
Doyle: “Well, I didn’t until last week. Then I saw what you did with your place and I just had to call my decorator.”

Doyle is referring to the episode Lonely Hearts, in which he saw Cordelia’s less-than clean apartment.

Spiritual Angel

The exercise Angel is doing in the courtyard of the mansion in Band Candy, is T’ai Chi Ch’uan, a Chinese martial art which is also used as a form of Taoist yoga. Snyder later says in that episode he learnt “Tae Kwan Do at the Y” - a marked contrast to Angel. In Revelations Buffy and Angel do T’ai Chi together, before it gets too sexy for them.
We also see Angel performing T’ai Chi in the Angel episode In the Dark.

Gem of Amarrah

The Gem of Amarrah was a legend amongst vampires. The Gem rendered the vampire who wore it invincible. Vampires combed the world for the Gem, but none found it and it was concluded that the Gem must be a myth, not unlike the Holy Grail. In The Harsh Light of Day, Spike discovered the Gem in a ring sealed in an underground crypt in Sunnydale. After Buffy got the ring from Spike she entrusted it to Oz to deliver to Angel, who destroyed it as he was worried it might get into the wrong hands.
In Heartthrob, after an invincible vampire attacks Angel and Cordelia, Cordy asks Angel if, “the Amarrah people [made] cufflinks or belt buckles?”

A Fistful of Dollars

In In the Dark, Oz says “Yeah, your old buddy Spike dug up Sunnydale looking for it - but he got a fistful of Buffy and left it behind.” This could be reference to the western A Fistful of Dollars.

Angela’s Ashes

In ‘In the Dark‘, Cordelia says to Doyle: “I think the trick is laying of the ale before you start quoting Angela’s Ashes and weeping like a baby man.” Angela’s Ashes is Frank McCourt’s autobiography about his childhood in Limerick, Ireland.

Batman

The comic Batman, by DC Comics, is mentioned several times in Buffy.

• In Some Assembly Required, Buffy says to Willow, “Sorry to interrupt, Willow, but it’s the Bat-Signal.” She’s alluding to the ‘Bat-Signal’ in Gotham city which is used to alert Batman that he is needed.
• In Halloween, Xander says to Cordelia, “Catwoman, you’re with me.” In the Batman comics, Catwoman is a cat-burglar, and the alter ego of Selina Kyle.
• In The Yoko Factor, Xander says, “You and Willow go do the superpower thing, I’ll stay behind and putt around the Batcave with crusty old Alfred here.” The Batcave was Batman’s high-tech base and Alfred was his loyal butler.
• The nerds’ freeze ray gun in Smashed may have been inspired by Batman’s Mr Freeze, who used a similar device.
• In Beneath You, Spike says, “A little touchy-feely, and you’re off to the Batpoles?” He’s referring to the 1960s TV show Batman in which Batman and Robin would slide down poles to the Batcave when they were needed.
• In Bring on the Night, Andrew mentions Batman’s foe The Riddler.
• Vincent Schiavelli, who played Jenny’s uncle in Surprise and Innocence played the Organ Grinder in the movie Batman Returns.
• In the Angel episode Lonely Hearts, Doyle says, “It’s not like you have a signal folks can shine in the sky whenever they need help, you know?”, referring to the Batsignal.
• In ‘In the Dark‘, Spike says of Angel, “quickly to the Angelmobile, away” - another Batman reference.
• In Benediction, Lilah says of Connor,”Who’s the boy wonder?” This is the name often given to Batman’s sidekick, Robin.

Fantastic Four

The Marvel comic Fantastic Four is referenced a few times in Buffy the Vampire Slayer and Angel. In The Witch, Xander says about Amber’s burning hands, “Like the Human Torch, only it hurts.” This is a reference to Johnny Storm, the Human Torch, a character in the Fantastic Four. In the Angel episode ‘In the Dark‘, Cordelia says “It’s daylight, you’re ringless, and unless you changing the act to Human Torch, I don’t think so”.
In Lessons, Willow’s Wicca teacher is named Miss Harkness. There was a witch named Miss Harkness in the Fantastic Four. In Bring on the Night, Andrew mentions the supervillain Dr. Doom from the comic.

The Flintstones

Whilst talking about Angela’s Ashes with Doyle in ‘In the Dark‘, Cordelia says, “I doubt very much that the main characters are Betty and Barney Rubble - as you so vehemently insisted last night. Also, I don’t think Oz apprecieated being called my little Bam Bam all night”
Betty and Barney Rubble are characters from the cartoon The Flintstones and Bam Bam is their child.

Versace

Cordelia references the fashion designer Versace in In the Dark when she says, “Since when did you get all Versace about accessorising?”

Seen at 36.04 minutes:

The boom mic can be seen on screen, just above Cordelia’s head in ‘In the Dark‘.