These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Big Lipped Alligator Moment: if you wander to a certain spot near Tenebrae, a mob of children attacks you, and if they surround you, you have no choice but to kill them. No explanation whatsoever is given for this.
The jumping puzzles in the release version caused many gamers to Rage Quit the game early on, since it was impossible to tell exactly where you'd land when you jumped. Subsequent versions allow you to target a specific point to jump to, though the Avatar can still get caught on seemingly invisible objects.
Also, the consistently trapped treasure chests. They explode even if you have the key!