I was trying to fight off some slimes and collect a mineral on one of the Royal Jelly's levels, but when I picked up the mineral I accidentally immediately picked up the one I dropped. I thought the mineral I dropped that time (the one I had meant to pick up) had disappeared, but it has just become transparent with a slight shadow. I didn't take a screenshot of the original issue, but I was easily able to replicate it again.

You can see it here: http://i130.photobucket.com/albums/p262/DirtTB/Spiral%20Knights/2011-05-...

Something else as well. If you guard, move, let your guard down, and then continue moving your shield does not reset to the normal size, it stays larger like it does when you guard.

See:
Original size: http://i130.photobucket.com/albums/p262/DirtTB/Spiral%20Knights/2011-05-...
Larger size: http://i130.photobucket.com/albums/p262/DirtTB/Spiral%20Knights/2011-05-...

Both screen captures were taken at roughly the same spot in the running animation. Nothing major, of course, but still a bug.