Accidental Innuendo: Lampshaded in the marathon episode. Shiro races out way ahead only to turn back because he's run out of white powder. Kou warns him that he shouldn't say that out loud in case a policeman hears him.
The openings and endings of both anime seasons, which have catchy beats and lyrics.
Galileo Galilei's "Sayonara Frontier" that was used as the j-drama's musical theme, especially the chorus.
Memetic Mutation: "Ah, I see that you're a man of culture as well." - A reaction image featuring a screenshot of Last Samurai, and this screencap is often accompanied by mock dialogues used to express good taste in a specific hobby or interest.
The live-action Mayor and Hoshi who appear in episode previews. Take account they are prop masks that look as realistic versions of the characters' masks, but they don't move as their animated or drawn counterparts... making them even more creepier.
The drama and its movie sequel don't follow the live-action aesthethic used by Studio Shaft in the anime for Hoshi or the Mayor, and the staff decided to go for make-up for the characters... but it's not a pleasant experience seeing the heavy yellow and green make-up on Takayuki Yamada and Shun Oguri's faces, respectively.