Revealing mistake: As Clark is chasing after the semi-truck with Lois and Lucy in the trailer you can see the Rocky Mountains in the background. Kansas doesn't have mountains. However, Vancouver, where the show is actually shot is home to part of the Canadian Rockies.
Revealing mistake: As Krypto presses the button to open Hercules' cage you can hear the button beep as if it has been pressed but the green light is still on. Earlier the beep which means the button worked also turns off the green light.
Revealing mistake: As the helicopter that Lana is in dodges the falling meteors in mid-air, the camera shot focuses in on the cockpit. If you watch Lana's position as she first starts to appear she is semi-transparent and the frame of the window behind her is visible through her body.
Revealing mistake: When Lana has her nightmare, she wakes up in a room and discovers various people on pedestals, underneath body sheets. During the scene, some of the people under the sheets can be seen lightly breathing, although everyone under them is dead.
Revealing mistake: When Lionel is playing the piano while talking to Lex, you see inside the piano and none of the dampers are moving for the notes he's playing, revealing he's not really playing or even hitting the keys.
Revealing mistake: When Pete is on his motorbike they pan to his face and we can see the stunt double. (04:36:00)
Revealing mistake: When Clark gets hits by lightning whilst trying to save Eric, you can see that Eric is a stunt double.
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