Usually, the door rattles either come from a loose window caused by a misalignment of the window, a missing or loose mounting screw (to fasten and hold the window brackets), or a screw or other metal piece inside the bottom of the door. One Spider I saw had a rattle because the door-stop retainer bracket had become loose and the inner bracket had loosened and dropped a piece of metal inside the door. One other possible cause is the door latch mechanism or the hinges. Have a look not only at the door itself, but also on the body where the door connects both front and back. Check for loose bolts and/ or missing pieces by comparing top the other door.
How to fix (if inside the door):
1. remove door panel
2. using a flashlight and a magnetic pick-up rod (available at any auto parts store), begin checking for metal debris inside the door.
3. using necessary tools, check each screw, bolt, nut, etc...to make sure all are tight.
4. check window by rolling it up and down and gently moving the window in towards the inside and back towards the outside. It should move a little, but it should feel fairly tight and well-connected to the window mechanism. Also check the window rubber and mouldings at the top of the door to make sure that the window is properly held in place whether down or up.
If you can't fix it then use this mantra:
"They all do that"
Cheers,