Continuity mistake: Jason Teague arrives at the Kent farm. He fires a shot into the windshield of the Kent's truck. So we obviously know the gun is loaded. Later, inside the Kent's house, Jason still has Jonathan and Martha held hostage. After Jason mentions the symbols burned into the field Martha says she doesn't know what he is talking about. Jason gets upset and racks the shotgun but when he does no shotgun shell, used or unused, is ejected. Now Jason would have had to keep the gun loaded while moving Jonathan and Martha back to the house as he would have had no time to unload and reload his gun.
Continuity mistake: When Clark is in the barn throwing footballs through the tire. He starts out with four footballs on the rack, but after he throws two, there's only one ball left.
Continuity mistake: When Lex finds Clark in the Talon doing his essay, he sits and talks with him. He puts his cup on the table and puts his hands in front of him. In the next shot, Lex now has his arms crossed in front of him on top of the table.
Continuity mistake: When Chloe finds Lois stabbed in the dam, we see Lois on the floor with her arm hanging so that her hand is right beside the stab wound. However in the next close up of the wound, her hand isn't there. It's back beside it in the next shot. (02:28:20)
Transference - S4-E6
Continuity mistake: Martha visits Lionel in prison not knowing Lionel is actually Clark. As she says "I'm only here because you told me it had to do with the safety of my son." the camera changes. Between changes, as Martha says "you", her left hand goes from being under the table to instantly being on top of the table.
Continuity mistake: When Victor is going into Lois' apartment with Clark and Lana, he is holding his jacket over his wound to soak up all the "blood". Later, when he goes to see his girlfriend, he is wearing his jacket, but his jacket has only a small stain now.
Continuity mistake: While Chloe and Lex struggle for control of the gun Simone puts both arms down to her side. The shot switches to a slow motion shot of Simone getting shot and instantly Simone has her hand on the jewel again.
Continuity mistake: Right after Ryan makes breakfast for the Kents, he leans on a chair and sets the orange juice jug down twice. (00:05:35)
Continuity mistake: When Chloe and Clark are at the Torch after the pool incident with Shawn, Chloe is sitting down wrapped up in a green sweater and a blue jacket with part of her blouse showing. In the next shot, she is fully wrapped in the green sweater. Seconds later, her sweater is tucked into her jacket and her blouse is showing. (00:28:00)
Continuity mistake: When Lana comes in with her brown bag of groceries, she puts the vegetables and wine bottle on the counter. During the rest of the scene these items move their positions a few times.
Continuity mistake: Clark rushes to get to school in Lex's car and we see principal Reynolds closing the gate to the school. In the close up, we see that the principal is off to the left of the lock of the gate. Cut to a different angle (his back to the camera) just as Clark arrives in Lex's car but now he is standing in front of the gate lock.
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: When Kara and Clark get off the elevator, there's no-one around them as they're walking away. In the next shot of Kara and the elevator, 3 people have suddenly gathered to look at the broken elevator. The elevator was off camera for less than 2 seconds, not enough time for 3 different people to get into the position they're in when they weren't close by to begin with.
Continuity mistake: When Lois is at the dam, looking at the card she previously tore, the numbers and markings are written differently than before.
Continuity mistake: When Lionel is watching the video and drawing Kryptonian symbols, some of the symbols change in between shots. For example, when he draws "minion" one of the dots is touching the square. When he writes the word, everything is nice and neat and the dots aren't touching anything.
Continuity mistake: After Lois pins the sketch of the Green Arrow, the pushpin changes position. In some shots, it's across the top of the paper and in others it's in between the top of the sketch and top of the paper.
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