Collector Trophy in The Bridge

There are seven wisps hidden throughout the game; when all are collected, they make a picture that you can see under the Trophy category in the options menu. The loading screens in the Mirrored Chapters each have hints as to their locations, but only a few are actually in the Mirrored Chapters.

It does not matter the order in which you collect them; the image will always unlock in a certain order. The hit box for them is a little flawed in your favor; often you just need to be very close to it/brush the “flame” part instead of the “core” part in order to collect it.

See below for locations and screenshots.

Chapter IV, Stage V: The Intersection
You likely got this on accident while trying to solve the puzzle. It's attached to the lamp closest to the veil.

Overworld.
Shift gravity so you're falling sideways, and fall through the tree branches 13 times. After the 13th time, you'll fall right past the wisp. Use rewind to back up and adjust your fall to collect it.

Overworld.
Enter the Konami code. No, really. Up-up-down-down-left-right-left-right-X-O. Do yourself a favor and do this inside the house to minimize the pain of collecting it. If you do spawn it outside, move until it's no longer on the screen and you can spawn it again.


Chapter I, Stage IV: The Courtyard
At the very beginning of the level, just hold the rewind button for about 60 seconds. The small hint the stage gives you is that the leaves on the tree keep going back into the tree, and the game doesn't “jolt” to indicate you've reached the end of your rewind time. Eventually, your character will fly up into the sky, where you'll see the wisp. Shift the stage around to control your descent; this is somewhat difficult as you can't see your character until just before you hit the wisp.


Mirrored Chapter III
In the stage select area of Mirrored Chapter III, keep walking to the left, past the doors, and you'll get it.


Mirrored Chapter II, Stage II: The Precipice
It's hiding on the candle. You need to slide yourself across the stage before shifting it so you wind up landing on the underside of the stage (while the stage is turned around so you don't fall off, obviously). This one has tricky timing, too, as you can't see your character most of the time that he's falling; experiment with inclines of the ramp and try to use the momentum of movement to nudge him over the edge instead of walking off of it.


Mirrored Chapter I, Stage III: Mirrored Menace
Timing, timing, timing. You're going to die a lot on this one. It's all quick rotations here. The goal is to get into the Bird area without being hit by the many Menace balls around. The excellent news is that unlike the original version, you do NOT have to do this all in one go! I rewound many times in my go and still got the wisp. It's tucked away in the corner and barely visible.