Continuity mistake: When Clark exits the phone booth wearing his blue shirt, only the neck button is unbuttoned in the wide shot. Immediately in the next close-up shot, two buttons are undone. Then in the next shot of Clark's front side, the shirt is back to only the neck button being undone. (00:02:27)
Continuity mistake: During a fight, the thug rips off the bra that Oliver Queen is wearing, rendering him bare-chested. The following shot, taken from a different angle (from the back), shows Oliver still wearing the bra whilst punching said thug.
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