During casting sessions, actors were asked to mime drinking a series of tequila shots with the director, and then dance drunkenly.
As the dance scenes were shot early on a Saturday morning, the extras on the dance floor were all either completely sober or still hungover from the night before. Some even arrived already wearing outfits made from trash.
The word "kichigai" is one of the most taboo words in Japanese vocabulary. A non-politically correct term for someone who is mentally ill, the use of "kichigai" has been banned from national TV. These days it is increasingly being used as a slang term for someone with some kind of addiction, or a social misfit.
The actor originally cast as Kei had to drop out due to conflicting schedules, and Shunya Tajima took up the role two weeks before production began. However Kei's character had originally been written with Tajima in mind.
As the golden nightclub is full of mirrors, each shot setup included a mirror check, to make sure that the crew couldn't be seen in any of the reflections.