You can shoot some advertisement boards on some buildings and they will fall inside the building.
If you then destroy the building the advertisement board is left floating in mid-air.
This bug can always be reproduced in the town of Somato on Sahrani, some advertisements fall inside the buildings and some others do not, but when the buildings are destroyed the advertisements are left floating in mid-air.
This bug has been in ArmA since its release and is still present in the latest 1.16 patch.