Pretty sure that shot's been edited, maybe sharpened or something. Scrapper isn't that orange in my HD copy of the trailer. As it is you have a colorful robot moving around in the background, not interacting with anything in the foreground, so of course it'll look fake.

 

I agree the Devs render is not finished. You can see the "pottery" getting sucked in looks cartoonish. Very few people in this forum realize how effin hard this scene is to put together.

As far as the sand goes, it's hard to recreat sand due to the finite texture of it. Meaning all the sand specs you have to enter in to make it look somewhat real is nearly impossible.

 

I think Bay said something about how they worked until just about the last minute of the last day before the film had to be shipped out on the first Transformers film as well.

Not totally sure but I bet there are plenty of effects driven films out there that were worked on right up to release date since effects people are always out to make it just a little bit better than even a few day ago.