Here's a screenshot of Cupid's pool at night from the back of the KQ4 box:
(On the box it was mistakenly mirrored, so I've corrected it here.)
Here's the pool at night as it looks in the original release of KQ4 SCI:
The starry night sky has been redrawn, and many of the trees are now visible in full color instead of appearing cloaked in shadow.
Also note the tree branch in the upper left corner. In the early version of the room, the branch bark was visible and the leaves were in shadow; now it's the tree limb that is shadowed, and the leaves which are visible.
In addition, look at the ground at the back of the screen; it was light green in the work-in-progress background, but now appears brown.
Here's the same pool at night in later releases of KQ4 SCI:
Because the new version overlays a night-sky backdrop directly on top of the daytime backgrounds, the whole scene is much brighter.
The small trees in the foreground are gone now, as with the daytime version of this screen, and the upper-left tree branch is now entirely in shadow. Plus, the sandy ground behind the pool is now much brighter.