At the very end of the movie, as the helicopter is flying into the sunset and the picture is getting ready to fade to black, if you look closely, you can see what looks like several cobwebs dangling across the lens of the camera. They're pretty easy to see because the light from the sun shimmers off of them. I notice this every time I watch the movie.
It can't be, even in the most amateur films the lens has to be totally clear otherwise the shot will not work, the slightest smear can ruin a shot. It is unlikely in a movie as expensive and professional as this that they forget to clean the lens.
Bigstu80's guess was my first guess too. But couldn't it also be that the glare of the sun(since the helicopter was going into the sun)caused the web like material to appear. If that's the case (and I could be wrong)this is not a slipup!
-SPORT