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.
Earworm: The openings and endings of both seasons.
Ho Yay: Takai is sometimes the Team Dad, but at other times he's got a serious crush on Kou. He has a Kou body pillow.
And it squicks even the most insane of the local bridge residents who noticed.
Uncanny Valley: The live-action Mayor and Hoshi who appear in episode previews. The faces are pretty realistic, which makes the fact that they don't move even creepier.
At least the drama and follow up movie adaptations weren't exactly so 'HARD' on the costumes. Though, well, Shun Oguri (who was the Mayor)'s and Takayuki Yamada (Hoshi)'s make-up weren't that... nice to see.
Viewer Gender Confusion: Amazoness' status is pretty unclear, given that she is very tall and the make-up she uses is... suspicious... but then again, without it, she's just a normal girl/woman.