Objects hanging in the air about cataclysm-dda HOT 2 OPEN

Meet this bag too several times, I get floating items by throwing into them rock or glass shards, it make them drop down

from cataclysm-dda.

The flower does not serve as a support. However, it's destruction may well trigger the call to an operation that checks if anything above doesn't have any support and thus should fall, even though no support was actually removed.

The error, however, lies in whatever places an item. It's probably some kind of map special that places the item on a location without the selection of which locations it can be placed on being coordinated with the placement (possibly because the location has been updated such that there isn't anything supporting that location anymore).
Item placement does not support items to "gravity" checks, but rather assumes that the placement has been selected to be in a legal location (adding checks may well slow down the game too much).

from cataclysm-dda.