Continuity mistake: While researching Greg with Chloe, Clark changes from one hand on the computer mouse to arms crossed and back. (00:34:00)
Continuity mistake: After Greg hits Clark with the pipe in the foundry, Clark's hands are very dirty. In the closeup on Clark's hand immediately after he lands, the hand is clean to show the effects of the Kryptonite. (00:39:45)
Continuity mistake: Clark's hair goes from long to short and back to long as Clark, Pete and Chloe talk about Greg's tree fort.
Factual error: When the bug kid crashes his car, he's driving a VW Beetle, which has the motor in the rear, therefore would not have shut off in a head on collision.
Deliberate mistake: The episode begins with a football game in pouring rain. After the winning goal is scored, the crowd shots show the cheerleaders' hair wet and their uniforms completely dry. (00:01:50)
Continuity mistake: As Lex is chalking his pool stick while talking to Dominic about cutting 20% of the workforce at the LutherCorp Smallville plant, there is a red snooker ball on the wall rack missing from the second row. When Lex walks over to the other end of the pool table, the camera shot changes back to Dominic, now there is a ball missing from the top row, which was not missing before.
Continuity mistake: While Clark and Jonathan are talking about Clark being on the football team, Jonathan puts his hands on Clark's shoulders. Between shots, the position of Jonathan's hands on Clark's shoulders repeatedly changes.
Continuity mistake: When "Lex" threatens the bank manager, he points the gun at his face, but the next shot on the manager shows the gun at his throat. (00:01:35)
Continuity mistake: Tina's grip on Lana's necklace changes as she stands over Lana's body. (00:37:30)
Factual error: Lana says the theme of her mother's prom was Saturday Night Fever, but she was in the class of 1977. Prom would take place sometime before graduation (which would be in May, maybe June), likely February or March. Filming for "Saturday Night Fever" didn't even begin until March 1977.
Revealing mistake: While Lana is listening to her Mother's graduation speech she reaches up to her neck for her meteor rock necklace. Her hands do not reach far enough back to unclasp the necklace yet the necklace comes off anyway.
Revealing mistake: As Tina/Clark tries to run over Martha, there is a shot of Tina/Clark up close in the truck, and the gear shift is still in park.
Visible crew/equipment: After Martha finds the money in the antique shop she tells the other woman she needs to be more careful, as they are walking in the room there is a boom mike shadow 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)
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