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.
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: After Clark enters the phone booth, he begins to change out of his red shirt. The phone booth is mostly frosted glass, but it is possible to make out that Clark only becomes bare-chested before the next shot when he comes out of the phone booth with the blue shirt on. (00:02:14)
Turbulence - S8-E16
Other mistake: In the article about the plane crash, the last paragraph starts to repeat the same sentence. After is says Mercer took over the operation, it repeats that she started in collaboration with Lex.
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