The scene where they show the cabinet members exactly how the planet is going to get cooked by cosmic rays. Yikes.
The destruction of the Golden Gate Bridge, as a tiny hole in the earth's layer caused one man's arm to instantly sunburn from being outside a car window. And then the bridge collapses in a way not unlike the Tacoma Narrows Bridge.
The lightning-storm that destroys Rome monuments and even statically charges coffee machines enough to cause a shock from touching them. Seeing such monuments the Colosseum explode without crumbling is very creepy.