Okay, so I'm at Daud's base in the Flooded district attempting to rescue my 1st assassin and using dark vision I'm watching the building across the way. On the floor below my assassin a overseer walks up the edge of the building and promply falls for no reason and screams"AAGH" on the way down. I really wished I had recorded it. Anything like this happen to anyone else?

There were no city guards on my level, did you mean a overseer? No nothing like that but that would have been funny to see.