In 1968, a team of Perkin-Elmer technicians were carrying the million dollar Copernicus space telescope mirror to the other side of the lab. They tripped over a piece of scrap lumber. Shaka, when the walls fell.
It was mentioned in http://www.terrydunkle.com/glass.php and in a Sky & Telescope magazine article from 1989 which explained why Perkin-Elmer began using very meticulous step by step procedure checklists after that. To prevent any major mistakes. Oh the irony.