I've seen pics of old Jaguars and they have this funky metal thing around the bridge, Is my Jag missing a part or what?
No you’re not necessarily missing any parts. The Original Jaguars came with a mute mechanism. It was a little strip of metal that was attached to the Bridge. It had a Rubber bar that touched the strings when the metal was flicked up. The rubber muted the strings so that players could use that instead of muting the strings manually with their hands. Players found it annoying and most just removed them.
When the jaguar was reissued in the 90’s as part of Fender Japan, the Mutes were not reissued because of their past failure. However if you have a Vintage Jaguar and no mute, you are missing that part. On a side note, the new American Vintage series Jaguars come with a reissue of the old mute.
[From Nick’s Jaguar FAQ]