really cool work,
if you need any help with mental ray in Maya just chuck me a PM.
just as a first thought, select all objects in the scene, and go to - edit - delete by type - history.
then try rendering it... might fix the problem
(if you dont do this, the scene builds up lots of cache files, and dead nodes that still influence the meshs and textures)
make a backup of your scene before trying this though
