For example on this savegame
http://sourceforge.net/apps/phpbb/freedroid/viewtopic.php?f=13&t=149&p=819#p816
on levels 12 and 42.
The savegame is likely "hacked", but I don't think that the items were dropped
intentionally.

We also had someone joining on IRC some time ago posting a screenshot with items
on level 42 (quite like the ones which can be found in the savgame) and didn't
know how they got there.