Infinite fall failsafe
In vanilla, when the PC is falling and reaches a point beyond which there's nothing to fall on anymore, the screen fades out and you're safely teleported above ground, usually the cell's 'center on' coordinates (DoorMarker...) for interiors. The bug itself infamously happens when jumping on faulty models in Vivec, or a number of occasions that can send you under the ground.
OMW doesn't seem to interrupt a fall into the void. Perhaps unrelated: full fall damage applies when using "center on cell" with the console in those conditions.
(RM-1415 from redmine: created on 2014-06-07 by rot tor, )