"This is what got me really interested in making the film: the way he's looking through the clock," Scorsese said.

http://www.cbsnews.com/8301-34.....onal-film/?tag=stack

This is interesting to me, because I suspect this is how it often works when a director or producer selects a film to make. It can really be just one simple aspect that grabs him. I haven't seen Hugo or read the script, but I would bet that this image comes extremely early on the pages. So that's the idea, create an image or scene that has the chance of grabbing someone. Once you've grabbed someone, if it's a film maker, they are inclined to look past or through flaws in the story, because they know they can fix them. These are intelligent people with a lot of confidence. They believe they can solve any specific problems. It's the premise, or an image or a scene, that really grabs them. I suspect, anyway.