thank you for trying our game. i know it's not perfect but glad you take your time for it.
items you couldn't pick up should be the pistol mod when you changed your gun. cuz it won't fit haha
i'm guessing you were reloading thus you can't shoot. maybe we need to improve a bit the UI to make it clearer.
if you're using chrome, i suggest you turn on "allow hardware acceleration" in settings. this will help you to have smoother gameplay for WebGL games.
hope this help :)