To fit a 600 page novel into a little over two hours clearly means that many scenes from the book will never make it onto the silver screen, however, at least a couple of hours of extra scenes were filmed, only to end up on the cutting room floor.
All films contain mistakes, or 'bloopers'.
Dune has its fair share, such as the tripping Navigator, find details of them here. Find details of them all here. Everything you ever wanted to know about the soundtrack is here. The Dune series spans 6 books, and more than a millennium. The New England Library covers of the first five Dune books join, end to end, to produce a landscape that covers time as well as distance, a Time-Scape.