I went back to the BMW website and read the end of lease FAQ section. They specifically state that if there is tint on the windows that you haven't removed, it automatically triggers a full inspection of the car by an independent agent. It also says that any modifications you can remove and return to stock prior to returning the car are ok. There is a good section on how the lease-end period works. Check it out.
2008 Sparkling Graphite 535i
2009 Land Rover LR2
2003 Porsche 911 Turbo (SOLD)
2006 Jet Black 325i (SOLD)
2001 Bullitt Mustang (450rwhp - SOLD)