Trivia: In the opening credits there is a shot of a girl standing alone on the corner of a street. This was taken from the Buffy episode "Anne", when Buffy was staying in Los Angeles.
Trivia: About 7 seconds into the opening theme you see the face of a young man looking up (Just before you see Angel with the sword) That young man is Phantom Dennis. He is only seen once in episode 5 of the 1st season- Room with an Vu. After that he's an unseen "character" until season 4.
Trivia: In the episode "Underneath", Illyria is talking about different dimensions she has visited and she says "And one world with nothing but shrimp...I tired of that one quickly." This is a reference to Buffy episode "Superstar": when Anya is explaining that there are many types of alternate realities, she says, "And there could even be a world with nothing but shrimp."
Trivia: Angel leaves the Reaper locked in a metal cage as the camera pans slowly back so we can only see his eyes - almost exactly the same shot as when Connor left Angel trapped in the metal coffin at the end of "Tomorrow". They even say the same thing - "You get to live. Forever". Like father, like son.
Trivia: In the episode 'Untouched' Angel asks Cordelia 'Do you have any idea how hard it is to think when you've got a rebar through you?', her reply of 'Actually, I do. Benefits of a Sunnydale education' is a reference to the BTVS episode 'Lover's Walk', in which Cordy falls through a staircase and is impaled on a rebar.
Trivia: In this episode, Cordelia makes a reference to "self-destructing tapes and a dossier". This is a reference to the 1966 TV series Mission Impossible, which featured self-destructing tapes used to send the main character on his assignment. An interesting fact is that Mission Impossible regulars Martin Landau and Barbara Bain are the real life parents of Juliet Landau, who played Spike's former love Drusilla during season 2 of Buffy.
Trivia: Cordelia and Wesley realize that the robbery is happening that night because the door latch is taped down - exactly the same way the guards at the Watergate Hotel realized a robbery was in progress in 1974, which led to President's Nixon's resignation. (00:27:20)
Trivia: By the series finale, Angel lost and regained his soul a total of three times: (1) in flashbacks to when he was sired and cursed, (2) after he slept with Buffy on her 17th birthday and re-ensouled by Willow, and (3) when Angel Investigations battled The Beast in season four (again re-ensouled by Willow). And while he didn't lose his soul in the episode "Eternity," he did briefly turn into Angelus; he also pretended to become Angelus in the Buffy episode "Enemies."
Trivia: When Angel is outside the observatory, he is dressed in the same clothes that James Dean wore in Rebel Without a Cause (a film where there are significant scenes at the same observatory), and Judy has a bit of the Natalie Woods about her too. They are also both set in the 50s.
Trivia: Joss Whedon hints at future events in season 4 during Lindsay's song in "Dead End." It hints about the coming of Jasmine: "The sky's gonna open, People gonna pray and crawl, Gonna rain down fire, Gonna burn us all," and "Pretty as a picture, She is like a golden dream." All references to Jasmine.