[If you mind spoilers, please scroll away]
The DDLC Posters seem...interesting...
I've noticed a few things, and I think that Sayori, Natsuki, and Yuri are recreating their death scenes in these posters.
Sayori doesn't appear to be wearing her school uniform. It's not just that her blazer's unbuttoned. Even though it was, throughout the game, her collar was always neat. In this poster, her shirt collar is askew: just like it was during her death scene. Is Sayori wearing the clothes she wore during her death? Also, the red strings are wrapped around her neck just like the noose was.
Natsuki never officially dies, but there IS the "Play with me" end where her neck snaps and she has a huge grin on her face. Surprise, the poster Natsuki's neck is in the same position, and she has the same creepy smile on her face.
And lastly, Yuri. During Yuri's death scene in the game, a bit of blood splashes onto her cheek after she stabs herself. Poster Yuri has a similar-looking smudge of blood on her cheek. Also, the red flower on the poster of Yuri seems to be blooming from the spot where she had stabbed herself in the chest.
(I'm aware that the posters aren't canon, but they are on the Team Salvato Store.)