Audio problem: When Mr. Luthor was buying the corn field from the farmer he says: 'Now, where do I sign?' The farmer replies: 'Right here Mr. Luthor' and points at the contract. Even though we can only see a profile shot of the farmer as he says these words it is pretty obvious that his mouth isn't moving.
Audio problem: While Sean and Whitney are tossing the football at the lake edge, at one point we hear Whitney catch the ball offscreen while the camera is on Sean. The camera then cuts back to Whitney and he catches the ball on screen. (00:03:20)
Audio problem: Sean drops frozen Jenna and she shatters. He then manages to casually walk out of the room over her without crunching any of the ice. (00:17:30)
Audio problem: When Sean flags down Whitney's truck, we hear his brakes squeal as he slams on the pedal. A few quick cuts later we see him do the same thing, apparently for the first time. (00:33:25)
Audio problem: Clark listens to his father and Earl talking in the hospital through the visitor window. The sound is the same volume and quality as when Earl was using the microphone, which he is not using now. Even if Clark used super-hearing to eavesdrop, it wouldn't sound the same as the microphone. (00:18:35)
Audio problem: After he breaks the methane valve, Earl runs to the security camera and whispers, "You see what you made me do?" His whisper is heard at the proper volume by the Luthors watching the camera, but the speakerphone is on the desk ten feet behind Earl, making this impossible. Most surveillance cameras don't have microphones. (00:28:55)
Audio problem: After Clark's parents come home, after their anniversary dinner, Jonathan and Clark go to see Earl in the hospital. As the Doctor says "It looks like he's got some sort of mineral poisoning, but its not from any mineral I've seen before." For the first few words of that line her mouth does not match up to what is being said but the dialogue, and her mouth slowly come together at the end of the line.
Audio problem: When the thief with one arm tells his other two buddies to "check this out" the shot switches to the right side of him. In that shot you can see this guy say "check this out" again.
Audio problem: The CD playing in Lex's car is heard at exactly the same volume and quality from outside the car when Lex has his windows up and when he rolls one down. (00:10:20)
Vortex (2) - S2-E1
Audio problem: When Lex talks to Clark, Clark clicks his flashlight on, and you hear the click signifying he has turned it on. But in the next shot, the flashlight is now off, without another click sound heard to signify that the flashlight was turned off.
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.
Audio problem: After Ryan collapses at Lex's, he and Clark are talking while Ryan is in the hospital. In the shot of Clark as Ryan says "I know what's wrong with me." Ryan's mouth is visible and you can see that he is not speaking the line as we hear it.
Skinwalker - S2-E10
Audio problem: In the barn, as Kyla and Clark talk about Skinwalkers, Clark says "like the legend of Naman is just a story?". When the shot switches to Kyla you can see Clark is talking but no dialogue is heard from him.
Audio problem: While talking about Tina Greer's suicide after Chloe says "lit a match" you can hear Pete say "okay" but you see his mouth doesn't move with the word.
Audio problem: When Whitney is tearing up the bathroom, he throws the door and we don't hear it land. I saw this on the DVD, so it was not a transmission problem.
Audio problem: After the DCA shows Clark and Jonathan the metallic key, Clark says, "We need to think about mom," but his lips are not moving.
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