Continuity mistake: When Kyle first confronts Rickman in his office and challenges him to a handshake, Rickman looks away. In the next shot on Kyle, Rickman is looking at him again. (00:13:20)
Continuity mistake: While Chloe and Clark are on the horses, and Chloe is talking about the surveyors from Rickman Industries, when the shot is on Chloe's side, Clark is holding his reins in his right hand which is resting on top of his left. When the shot switches to Clark's side, as Chloe continues the story, and now Clark's right hand is under his left.
Continuity mistake: When Kyle goes to confront Rickman about coming to Smallville, Kyle is talking about how Rickman agreed not to do anything in Smallville and Kyle is pointing with his left hand. When the shot switches he is now pointing with his right.
Answer: The kryptonite only creates mutations when it reacts with the environment and an individual. Remember, the FDA and several environmental groups did check out Smallville after the meteor shower, but found no danger in the rocks. Obviously they're not always emitting mutating rays, or all the flora and fauna of the surrounding area would be horribly mutated.
Phoenix