It doesn't sound good. On my 2011 everything is packed in pretty tightly so the parts probably wouldn't move around much even if they were all unscrewed. The "retina" machines are even smaller so I can't imagine that there should be anything moving around in there either...
Those lithium polymer cells are very fragile and if it were to come completely unglued (which it might do), the wires connecting the cells could rip and short and cause a fire. Seriously. Take it in.