The phosphors of the screen may indeed have cadmium in there, and there is probably a little button of barium metal inside the tube itself. Also remember that there is a VERY high vacuum inside that tube, and if you attempt to open it up there's a chance it could implode on you and send shrapnel all over the place. In addition, the capacitors in those old CRTs hold onto their charge for a good long while, so if the tube isn't properly discharged, as well as all of the other capacitors, you may severely hurt yourself with a vicious electrical shock.