Audio problem: Clark says "What if it's some sort of high tech crop duster or something?". Pete replies with "She'll never let us live it down." After the shot changes you can see Pete's mouth say "live it down" again with no sound coming out.
Audio problem: After they get the spaceship into Pete's shed, Pete wants to go tell Chloe. Clark insists that he doesn't and Pete says "To her, this thing is the Holy Grail.". The shot zooms in and Pete's mouth shows him saying "Holy Grail" again even though he already said it and you don't hear the words.
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