Hey all,
To elaborate on Tyler's post, when Nikto fires the cannon, Fett has luke trapped in the lanyard, but he still deflects the blast with his saber, causing something behind Fett to explode, thereby causing said damage. As far as the SE caps with the damaged pack; that's just poor planning—They have the wrong helmet anyway! And why in the ANH SE is he wearing the ROTJ suit? Poor, poor planning!