Continuity mistake: In Kandor, Superman punches a hole in the ground and picks up a large chunk of the street out of the hole, but does not move from that spot. The shot changes to the robot's perspective of him about to throw the rock and shows his feet. The ground he just punched and picked up is in perfect condition at his feet. No hole, no cracks, no sign of the damage he just made.
Picture added by Quantom X