Ryoko Hirosue didn't know a word of French; she learned all of her lines phonetically.
The wall art that Yumi envisions for her room was taken directly from liner notes of The Prodigy's album 'Music for the Jilted Generation' which features the song "Voodoo People" that was used in this movie.
On Miko's empty apartment, the window shows a neon light advertisement with the Japanese words "raw wasabi"
In the arcade, the game that all the young characters convince Hubert ('Jean Reno') to play is "Dance Dance Revolution". Before you see the DDR machine (it's a 5th Mix), many of the other music-related games that are shown are also part of the Bemani series, including Beatmania and many others. The song that the characters play is 'Dive' by BeForU, and Jean Reno's character does fail on the easiest difficulty level (Basic Mode, known in more recent generations of the game as Light Mode).