If I recall correctly, in the original show, the bad guys kept Earth Benders on a metal boat out at sea to prevent them from using their powers against them, but in the live action movie they kept them in a valley surrounded by rocks, which makes no sense because they would be able to use their powers and fight back against them easily there.

Also when they did use their powers to fight back in the live action movie, they basically did little more then throw rocks that anyone could easily pick up by hand.