Though credited with a question mark, the voice of Miyu Miyu is provided by Evangelion director Hideaki Anno.
Amarao's eyebrows are actually sheets of "nori", dried seaweed that is used in sushi. The nori was digitally scanned into a computer.
Director Kazuya Tsurumaki personally oversaw the English dub in America. He was very insistent that the voice actors/actresses from the English dub had the same "essence" as the Japanese actors/actresses. He said he was very pleased with the characters for the English dub, and was especially pleased with voice actress Kari Wahlgren's Haruko.
The Vespa seen in the closing credit sequence belongs to director Kazuya Tsurumaki. Apparently, he can't get it to work.
Despite the title's spelling, the title is intended to be pronounced "Furikuri" ("Fooly Cooly" in English), not "eff-ell-cee-ell." The letters "FLCL" are a romanization of the four Japanese Katakana characters that spell the title. "Furikuri" is an oft-repeated term by the characters but its meaning is never specifically explained.