The door for the vanity mirror (or the frame for the door) can break; due to a redesign, the mirror "cassette" will need replacement.Google+
Car Problem Reports
Mercedes-Benz S500 Vanity Mirror Door May Break
Mercedes-Benz S500 Problem
Average Mileage: 86,566 mi (14,500 mi - 140,000 mi)
Visitor, 2000 Mercedes-Benz S500, 110,000 mi
Purchased vehicle in 2006 with broken passenger vanity mirror door.
Visitor, 2001 Mercedes-Benz S500, 65,000 mi
both Lt and rt vanity lights inop. I'm guessing new visor asm.
Visitor, 2000 Mercedes-Benz S500, 125,000 mi
I am still looking for a fix.
Visitor, 2002 Mercedes-Benz S500, 16,000 mi
Passenger vanity mirror, plastic arm broken
Visitor, 2006 Mercedes-Benz S500, 98,000 mi
Both vanity mirror frames cracked.
Dealership replaced it but it broke again so I just left it as is. It will not move to up position constantly drops down as a sun visor even when I don't want one.
Visitor, 2003 Mercedes-Benz S500, 117,000 mi
Vanity mirror door broke
Visitor, 2000 Mercedes-Benz S500, 130,000 mi
Purchased the car with a broken driver side vanity mirror door. I glued it shut temporarily until I get around to replacing it with a new one.
Visitor, 2006 Mercedes-Benz S500, 70,000 mi
Yes, I have a similar problem at the driver's side.
Visitor, 2004 Mercedes-Benz S500, 47,000 mi
Both Mirror framws broken.