Character mistake: Chloe hands Clark a newspaper with the list of jury members from Harry Volk's trial. As he reads the list he says "Rudolph Gage, Rita Garfield". After Clark realizes that his grandfather, Hiram Kent, is on the jury he hands the paper to Lana. A shot of the newspaper has the jury members listed as Randolph Gage, and Eve Garfield. Even young Harry calls her Eve when confronting Zoe at The Beanery.
Character mistake: While Clark and Chloe are at Daily Planet, Clark asks her what is wrong with her mother. Chloe responds that her mother left when she was twelve years old. In the episode Lineage, Chloe and Clark are looking for Rachael Dunleavy and Chloe says her mother left when she was five.
Character mistake: Chloe is looking at her digital wall of weird for anyone with camouflage abilities in the past and says there's no match. They act like this is a new power. However, in season 1, "Shimmer", Jeff Palmer had the ability to turn invisible because of a cream he made with kryptonite infused green roses. That should have popped up in her search. And even if it didn't, Chloe should remember the ability to turn invisible because she got the cream on her fingers, which turned invisible.
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