Liam/Angel was born in 1727 and turned into a vampire in 1753, as established in Angel: The Prodigal (2000), and he counts 1753 as his birth year. Although he spent 100 years in a hell dimension due to Buffy's actions in Buffy the Vampire Slayer: Becoming: Part 2 (1998), he does not count those years as part of his lifespan and told Cordelia in Angel: Dear Boy (2000) that he was 247. Allowing for aging, he is 251 years old at the series end.
The WB's announcement that it was canceling the show came at a time when it was rated second only to Smallville (2001) among 18-to-34-year-olds. Earlier in the same month, WB's weekly ratings release revealed that "Angel" had earned "outstanding year-to-year gains" among demographic groups.
In the opening credit sequence of every episode, there is an image of a woman standing by the side of a street. This is not actually taken from any episode of Angel but rather it's from the Buffy the Vampire Slayer: Anne (1998), though the scene takes place in the show's setting of L.A.
Vincent Kartheiser has said on interviews that the character of Connor lost its thrill for him very early on, arguing that his conflicts were not well explored and that after a while most of his scenes felt repetitive.
A key location in Angel's life is the Hyperion Hotel. In Greek mythology, Hyperion was the Titan god of light, and the father of three gods who were themselves "light-givers"--Selene (goddess of the Moon), Helios (god of the Sun), and Eos (goddess of Dawn). This is a reference to Angel's vampire inability to withstand the light of the sun.
The character Doyle wasn't originally supposed to be an Irishman but was written as such when Glenn Quinn was cast as Doyle. The role of Doyle was Quinn's first role where he was able to use his own Irish accent.
It was originally intended for Angel's sidekick to be Whistler (Max Perlich) who appeared the "Becoming" story arc of Buffy the Vampire Slayer (1997). But when the actor couldn't commit to a series, the character of Doyle was created.
The character played by Julia Lee who first appeared in Buffy the Vampire Slayer: Lie to Me (1997) as the self-named "Chanterelle," reappeared under several different names over the runs of both Buffy the Vampire Slayer (1997) and Angel (1999). At the start of her next appearance on "Buffy" (Buffy the Vampire Slayer: Anne (1998) she had changed her name to Lily; during that episode, she states she had once joined a cult that had renamed her "Sister Sunshine;" and at the end of the episode, Buffy gives her both a job and her newest sobriquet, "Anne" (Buffy's real middle name). By the time the character first appears on "Angel," she has kept "Anne" as her first name and added the last name "Steele" to it. Although it is never mentioned onscreen, the original teleplay for "Lie to Me" indicated that her original name was Joan (which is also the name that Buffy chooses for herself when she has amnesia in Buffy the Vampire Slayer: Tabula Rasa (2001).
The songs that are sung to Lorne by Lindsey in Angel: Dead End (2001) and by one of his clients in Angel: Sleep Tight (2002) were both written by co-creator and executive producer David Greenwalt, as was the title theme to Cordy's sitcom in the fantasy sequences in the episode Angel: Birthday (2002). That song was sung by both Greenwalt and consulting producer Marti Noxon, who also appears in the sequence.
Each episode has quick flashes of images between most scenes. In Angel: Epiphany (2001), for instance, between the scene with Angel and Darla and the scene where Angel goes to save Kate, there is a quick flash of a crew member holding a slate marker.
In the beginning of the show's first season, whenever Cordelia would answer the phone at Angel Investigations, she would say, "We help the hopeless." That line was later changed to "We help the helpless."
In the DVD extras, production designer Stuart Blatt describes how Joss Whedon and David Greenwalt wanted "a very real feel" to the Hyperion Hotel in the sets. The suite which Angel uses as his own apartment, the "Honeymoon Suite of the Hotel," had many other uses. It was also Cordelia's apartment when she told Connor that they were going to have a baby. It was also Fred's room, for the few times that we see her with Gunn in a bedroom. Because the crew could repaint and move the walls around, that set was the scene when Angel saved baby Connor from a fire; and later, it became Jasmine's suite. Blatt describes Jasmine's as "the mother of all suites ... part Oprah Winfrey, part Liberace, all decorated by Lorne."
The trivia items below may give away important plot points.
Charisma Carpenter was reluctant to reappear on the show after her character was written out. When she was asked back for the 100th episode she reluctantly agreed on the condition that her character did not die. After signing the contract to appear in the episode she was informed that Cordelia would die in the episode and was so upset that she began crying.
Sarah Michelle Gellar was offered the chance to reprise her role as "Buffy Summers" for two episodes of season five. Gellar was scheduled to appear in the 100th Episode, and was going to appear, but had to cancel at the last minute due to a death in her family. Joss Whedon also wanted her back for Angel: The Girl in Question (2004), but she couldn't commit because she was filming The Grudge (2004) at the time. Later on, Gellar informed creator Joss Whedon that she was open for the series finale, but he was against it and turned her down because he wanted the last episode of the series to be about Angel and the ones he'd "been in the trenches with," rather than a guest star.
According to an interview, Nicholas Brendon who had played Xander on Buffy the Vampire Slayer (1997) offered to jump to Angel (1999) after the Buffy finale on UPN. However, the producers turned him down, "because he wouldn't fit in."
Andy Hallett holds the record for the actor who took the longest to become a regular. He guest starred in over 40 episodes during the second, third, and fourth seasons before finally being added to the main opening credits of the 14th episode in the fourth season.
It is a widespread misconception among viewers of Buffy the Vampire Slayer (1997) and/or "Angel" that the character of Angel can't have sex without losing his soul. In fact, this was never stated on either show. Although he did lose his soul after having sex with Buffy for the first time (Buffy the Vampire Slayer: Surprise (1998) and Buffy the Vampire Slayer: Innocence (1998)), the curse that caused that stated only that he would lose his soul when he experienced "a moment of perfect happiness," something that not every sexual encounter affords him. For examples, he kept his soul after having sex with Darla in season 2 of "Angel" because the encounter did not make him feel happy. Even his brief love/sexual relationship with werewolf Nina in season 5 was just tender and not passionate - and very far from perfect happiness, because of the "demonic-political" problems he has.
Barry Manilow's "Mandy" makes a few appearances in the series. Angel sings the song in Angel: Judgment (2000) and the end credits roll over that as well. In Angel: Orpheus (2003), we see Angel play the song on a jukebox in one of his flashbacks. In Angel: The Magic Bullet (2003), Angel and Connor sing the song, replacing "Mandy" with "Jasmine".
Spoiler for Season 4: On the DVD extras, Production Designer Stuart Platt reveals that one set was used for many purposes: for the basement in which Angelus (when his soul was removed) is imprisoned behind bars; for the upper loft where Connor and Cordelia were hiding from the rest of the gang; and as the room in which many fights occurred, such as ninjas crashing in through windows and the gang fighting.
Spoiler for Season 5: After being listed as a guest star on both this show and Buffy the Vampire Slayer (1997) for the previous eight years, Mercedes McNab was finally added to the opening credits of "Angel" for the final six episodes.