While I'm aware maybe it's just on me to understand how dropping items works, but I think it could be made clearer -- the hotkey mostly. And I think it should be made so that it's not easy to do on accident. I just dropped a diamond pickaxe somehow. I don't know where, I don't know when, I didn't notice at all. That's a few hours of work (a few thousand pixels total, diamonds which are very hard to find) and there's nothing I can do about it. Kind of makes me want to quit playing the beta because it's a rather significant setback.
Q makes you drop whatever your currently holding, if you read the codex, the one about controlling yourself, it will tell you the controls. As of a side note, it's a bummer when you drop something and didn't realize it till it was too late.
The hot key is 'Q' which is very problematic sense your hand is constantly near 'W' and 'A'. Needs to be changed