Angel Season 5 Episode 10

Lindsey: (referring to Spike) I mean he hasn't sewn a big red S on his chest yet.
Lindsey makes a reference to DC comics superhero Superman, who has a big S on his chest.

Gunn: We open a can of Machiavelli on his ass.
Niccolo Machiavelli wrote The Prince in 1513. The manuscript outlines the characteristics of a successful ruler and is the source of the infamous quote, "The ends justify the means." Machiavelli has become a symbol for ruthless tactics and The Prince has been found on the bedside tables of leaders a diverse as Lincoln and Hitler. There is much debate over whether the piece was written seriously or as a satire of the powerful Medici family.

Lindsey: From what I hear Angel didn't save the girl on his first mission.

This refers to the first episode of the series "City Of" (1x01) in which Angel fails to save Tina, the first "helpless" that Doyle's vision sent him to save. The vampire who killed Tina, Russell, was Lindsey's client.

Angel: Gunn, get a meeting with your best Judas.
This refers to Judas Iscariot, one of Jesus's disciples who betrayed Jesus by alerting the Roman soldiers to his location. The term "Judas" is now often used to describe a traitor.

Fred: walking toward Angel in a field

This may be a reference to the television series Touched by an Angel. There is a very similar scene in the opening credits of that show in which a woman in a flowered dress (very similar to Fred's) is shown walking through a field toward the camera.
The connection with an angel may refer to Angel's perception of Fred, may be a foreshadowing of later events, or may even be a pun on the names of the two shows.

Wesley: ...deserves to become a real boy.
Fred: You're human!
In one of Angel's dreams, the Blue Fairy makes Spike human again (a "real boy" as Wesley put it). While Pinocchio was not a vampire, he was not human either, he was a puppet carved by Geppetto. The Blue Fairy gave life to Pinocchio but he wanted more, he wanted to be a real boy (human), and eventually, after earning it, he became one.

Harmony: It's "Match-a-belli," Einstein, and it doesn't come in a can.
References Prince Matchabelli perfume, a perfume line belonging to Perfums de Coeur and includes Cachet, Windsong, and Aviance Night Musk.

Spike: Sorry Mr. Vader, but I don't have an itch to join the Evil Empire
Spike compares Wolfram & Hart to The Empire from Star Wars. He also calls Wesley Mr. Vader as in Darth Vader from Star Wars.

Wesley: The vigilante reportedly killed two vampires at a gas station, then asked the women he saved if they quote "wanted to get a bottle of hooch and listen to some Sex Pistols records with him."
The word "hooch" is a long-used slang term for low-quality alcohol, usually whiskey. The word originates from alcohol that Alaskan natives made and sold to miners during the Klondike gold rush.

Spike : Well, look who's come to call, Crockett and Tubbs.
Det. James 'Sonny' Crockett and Det. Ricardo Tubbs are the two main characters from the hit 80s TV Show Miami Vice

Lorne: Sing out Louise.
This is from the musical "Gypsy." Mama Rose tells Louise (later Gypsy Rose Lee who is a famous burlesque stripper) to sing out because she can't sing loud.

Wesley: The vigilante reportedly killed two vampires at a gas station, then asked the women he saved if they quote "wanted to get a bottle of hooch and listen to some Sex Pistols records with him."
The Sex Pistols are a punk rock band from England who often sung of anarchy. They were headed by front man Johnny Rotten, but broke up in 1978 because Rotten felt that they had become a commercial gimmick, they reformed minus one member in 1996 for a tour.

Fred: Hmm. Came up the gulf stream, huh?
When Fred pulls the bent license plate out of Angels chest it is a reference to the movie "Jaws" where Richard Dreyfus is removing the contents of a smaller shark's belly and finds a license plate. The quote; "Musta swam up the Gulf Stream"; is also what he had said when he found the license plate.