Christian Kane (Lindsey) originally auditioned for the role of Riley Finn on Buffy - Im Bann der Dämonen (1997). Show creator Joss Whedon liked Kane so much that he asked him to play the character of Lindsey instead.
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" episode Anne (1998), though the scene takes place in the show's setting of Los Angeles.
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.
During his Season Four storyline arc as Angelus, David Boreanaz was allowed to improvise many of his lines.
The character Doyle wasn't originally supposed to be an Irishman, but was written as such when Glenn Quinn was cast. The role of Doyle was Quinn's first role where he was able to use his own Irish accent.