Continuity mistake: While Earl is in the hospital bed, his grip on the microphone to the waiting room changes from up to down and back. (00:17:55)
Continuity mistake: For several shots during the early scene with the baby in the crib, the blanket changes back and forth from tucked up to the chin, up to the shoulders, and up to the stomach in different angles. (00:01:55)
Continuity mistake: At the beginning, as the mother tucks the blanket up to the child's neck, she changes from both hands on the infant to one hand on the crib. (00:01:55)
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