Since we're adding to the secrets here. On my 2nd play through and trying to get cut scenes with Natsuki I stumbled across an interesting "secret" of sorts.
This happened during the 2nd or 3rd poem creation portion, after Sayori's suicide and the game is corrupted/hacked. I picked a random word that I thought would trigger Natsuki but ended up triggering either Sayori or Monika's chibi paper cutout that was off the bottom of the screen.
I sadly don't recall what word triggered it but was surprised to see a cutout off screen. Anyone else have luck triggering this?