Factual error: Lana is trying to find out what Lex is up to. She gets a hold of his briefcase and takes it to the mansion where she shoots the locks off the case. When she does the case jumps a little bit but this is far less than it should. She is shooting at it from less than a foot away. The force of the bullet should have sent that case sliding across the desk at that range. (00:15:35)
Factual error: The last scene is said to be set in "Iguazú Falls - Patagonia, Argentina." Iguazú Falls are nowhere near Patagonia. (00:40:00)
Audio problem: When Jimmy is in the 1940s Talon we can hear the sound of a saxophone in the number before Lois arrives. Nevertheless, as we can see on the stage, there are only three instrument: a drum, a piano, and a bass. (00:52:00)
Continuity mistake: Shortly after their cell phone conversation, Lionel sees Lana and gets out of his car. In the next shots of Lionel, his car has moved position from behind him.
Continuity mistake: At the beginning of the episode, we see that the clock reads 2 o'clock. Jimmy then takes Chloe into the back room to his set-up movie date. A little into the scene, they then hear a gunshot. When they rush out, the clock now reads 4:15. However Chloe and Jimmy were not in the back room for this long. At 4:15 they find Lana shot, and call 911. Then after the credits, we return to the scene, but now the police have arrived. But now the clock reads 2:15. There is no way the police would have taken so long, that the clock would have jumped all the way around from 4:15 to 2:15, therefore the continuity on this clock is mixed up.
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)
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.
Other mistake: When Clark looks at Oliver's newspaper clipping, there's a story about an AIDS hospice being saved. But the 2nd paragraph on talks about the 2nd meteor shower to hit Smallville that has nothing to do with the hospice being saved.
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.
Other mistake: When Jimmy wakes up in 1940, on his desk calendar it's Saturday the 3rd. The newspaper says it's May 3rd, 1940, but that was a Friday.
Other mistake: The bowling scorecard for Chloe and Lana is wrong. It shows Chloe knocking down 1 pin (-|1) in the first frame but getting 3 points, then a spare in the 2nd frame but only getting 1 point. The math is wrong until the 7th frame where is ends up showing the correct score. Lana's score is correct, except on frame 9 it shows she knocked over 6 pins on her first ball and is on her 2nd ball, but when it cuts to her, all 10 pins are up. Plus an unfinished 9th frame shouldn't show a score.
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