Hurt Yui Glitch (Chapter 2) Edit
When playing as Ms. Yui, In classroom 3-A, approaching the shelf will trigger Yui's "hurt" dialog, after the normal description dialog.To trigger this event on PC, approach the shelf and stand directly right of the it, facing to the left. Examine the floor and it will activate the glitch. It will not work if Yui is facing down, or right.
Double Ryou Glitch (Chapter 2) Edit
The double Ryou glitch can occur at any point in the game when Ryou is spawned.
In some instances, it is caused by faulty scripting. During chapter 2 where Ryou spawns after you exit the entryway, the game expects you to go back into the entryway, as you cannot go past Ryou. However, if you have the amethyst here, the game does not respond to it properly and hence doesn't actually de-spawn or stop Ryou as it should, but instead glitches out and creates another Ryou that responded to the amethyst script, along with the original that doesn't respond. Walking back into the entryway de-spawns the original Ryou, but the other one again isn't scripted to respond to that de-spawn and thus will still exist, meaning that you now have one Ryou that doesn't respond to de-spawns, and the other that is the correct one.
Since the game already detects Ryou roaming about when he shouldn't be, it creates another glitch where the correct spawns of the actual Ryou do not trigger. In other words, the Ryou that should be roaming the hallways after you exit the entryway for the second time is never there.