When the dome lands, it cuts a cow in half, which slumps the ground, sliding on the surface of the dome. It leaves no blood behind on the dome's surface, yet when Dale touches it with his blood covered hand, it leaves a bloody hand print behind. The cow should have left blood behind as well.
At the beginning the government send a bomb to destroy the dome and the destruction outside the dome is seen. In all the others episodes and seasons, even only few days or weeks passed, everything is green with no signs of been hit by a bomb.