Trivia: Sympathy for Lady Vengeance
- Hey, It's That Guy!: Song Kang-Ho and Shin Ha-Kyun (ie. opposing protagonists Mr. Vengeance and Ryu from Sympathy for Mr. Vengeance) briefly appear as hired assassins who get shot by Geum-Ja.
- Returning from Oldboy, there's Min-sik Choi as Mr. Baek (previously Dae-su Oh), and Byeong-ok Kim as The Preacher (previously Mr Han). Very brief cameos from Oldboy include the Hye-jeong Kang as the announcer at the very beginning (previously Mi-do), as well as Ji-tae Yu as the grown up Won-Mo (previously Evergreen).
- Especially notable are Kwang-rok Oh and Dal-su Oh, who appear in all three films: Kwang-rok Oh is an anarchist in Mr Vengeance, the suicidal man in Oldboy and one of the parents at the end of Lady Vengeance; Dal-su Oh is uncredited and in only one scene at the beginning of Mr. Vengeance, is Mr. Park in Oldboy, and is Mr. Chang the bakery owner in Sympathy for Lady Vengeance.
- Market-Based Title: The US release shortened the title to Lady Vengeance due to the poor box office result of Sympathy for Mr. Vengeance.