I found the mirror but when i activated it, it said : lacking visitors. No face appeared in it but I have a quest that says to find the target that should appear in the mirror.
I found some pink hearts too but I'm not sure what they do or how to interact with them. also found a treasure chest but when I opened it, it was empty.
I'm not sure if this is intended but here's some things I noticed about the movement :
-crouching lets you dodge every arrow
-dashing in the air lets you skip pretty much anything, i never used the crates to jump on them
-when you jump on a wall you can wall jump at some angles
-crouching and jumping lets you jump double the height of a normal jump