I haven't played too far, but did notice that sometimes my characters would be at "the edge of ____ (and I never really knew why)." The best I could do was click on their avatar (picture at upper left), which would attempt to zoom "closer" to them. At that point, I guessed they were against a wall that I couldn't see. I moved them to another area, but it made me wonder, were they on some sort of balcony or overhang?