2. Grave Of The Fireflies
Studio Ghibli's Grave Of The Fireflies released all the way back in 1988, but it wasn't until quite recently that a dark secret about its poster was uncovered.
The movie is set during the Second World War, and follows siblings Seita and Setsuko as they seek refuge during the final weeks of the conflict. It's a very grim story: Seita and Setsuko's house is destroyed, Seita is beaten, Setsuko becomes ill, and in general, the bad events never seem to end. Still, there's an undercurrent of hope running through the whole film, despite the saddening note it concludes on.
And the poster seems to embody that hope, showing the siblings laughing while playing with some fireflies. Only, there's more going on here than first meets the eye.
By altering the poster's brightness and contrast settings, a gigantic bomber plane becomes visible at the top of the image. Even worse, it then becomes apparent that those fireflies aren't all fireflies - take a closer look at the ones directly below the plane, and you can see that they're shaped like bullets.
Now, the film is hardly a bundle of laughs, but designing a poster showing two kids getting blown to bits by a huge aircraft is just a little bit sadistic if you ask us.