The arrows on the elevator buttons clip with the actual buttons.
In the staircase on this side,
the collision mesh on the handrails are horizontal, not slanted (you can float in the air near the bottom, and clip through on the top).
Also, the bottom of the bottom staircase has an invisible block that doesn’t let you under
and this wall has dev textures (that’s on floor 3, by the way).
None of these happen on the other side.
Lastly, these lights on the ceiling are floating in mid-air.
I also think the ones on the upper-most floor are floating as well, but it’s hard to check.