Found this location in River City on accident and got stuck there. The issue seems to be that you can't reverse out of the spot due to the girder next to the road.
The way to get stuck is to walk up the broken bridge in F5 to the twin towers and then walking forward just a bit, which causes you to slip and slide for a while. Usually you are eventually spat out by the mech jiggling around a bit so it's not a guaranteed stuck, but I managed to get stuck there properly without being able to get out once more trying to replicate the bug. I think that having the girder be breakable/have no collision could fix it.
Here is an album showing the location and happenings (still don't know how to upload images to the forum directly ^^')
https://imgur.com/a/osNMc94