Vortex (2) - S2-E1
Audio problem: When Lex talks to Clark, Clark clicks his flashlight on, and you hear the click signifying he has turned it on. But in the next shot, the flashlight is now off, without another click sound heard to signify that the flashlight was turned off.
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