Visible crew/equipment: As Chloe is running from the truck there is a shot where you can see the camera shadow on her back as she is completely turned away from the truck.
Audio problem: Just before Adam says "If I read something in out friendship that wasn't there." the camera shot is focused on Lana but you can see Adam's mouth in the top left of the frame. In that shot you can see Adam's mouth is saying the line before we hear it.
Continuity mistake: As Lana starts her second swing at Chloe with the axe while the camera is in front of Lana Chloe is just barely getting up and is still close to the floor. The camera switches in mid-swing and suddenly Chloe is completely standing and is able to jump back to dodge the swing.
Continuity mistake: When Molly first starts flipping through the disks for Lex, she has a ring on her left ring finger. After Lex talks about just getting back Molly is shown still flipping through the disks only now the ring is gone.
Revealing mistake: The computer that Molly takes the hard drive from is shown as having no power cord plugged into the back of the unit. With no power being supplied to the unit the hard drive would not be displaying a picture on the monitor, the monitor itself maybe plugged up but no signal from the computer would be going to it, and we see that the wallpaper on the screen is immediately taken off when Molly unplugs the hard drive.
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