The names of the "Paper Sisters" are loosely inspired by three famous Hong Kong actresses: Maggie Cheung, Michelle Yeoh (who has also been credited as "Michelle Khan") and the late Anita Mui. Alternatively, a possible reference (pertaining to Anita's surname) is Hong Kong actress Michelle Reis, whose surname means "king" in Portuguese (her father being Portuguese).
Woo-san, the pigeon in the series, is named after Hong Kong action director John Woo. John Woo usually has a shot with a pigeon flying in his movies.
Akage no Anne (Red-Haired Anne), the book that Hisami reads, is the Japanese adaptation of L.M. Montgomery's classic novel Anne of Green Gables.
The final remark made by Yomiko in the series finale (referring to paper "being in the heavens") is a pun in Japanese. The word for paper, "kami" can also be written (using a different kanji) to mean "god(s)." Taken in context, it becomes an indirect reference to a quotation from Robert Browning: "God is in His Heaven, all's right with the world" - a fitting way to mark a happy ending.
R.O.D -The TV-'s subplots use a lot of references from classic novels like Ray Bradbury's Fahrenheit 451, H.G. Wells' War of the Worlds and Arthur Conan Doyle's Lost World.