Skinwalker - S2-E10
Continuity mistake: While he is being attacked by the wolf the foreman fires the flare gun with his arms spread, meaning that it would fly at an angle away from him. He then sees it arcing back from below toward him, impossible unless the flare changed direction and location in the air. (00:02:20)
Skinwalker - S2-E10
Continuity mistake: When Lex is talking to Lionel outside the building site at the end, Lex's sunglasses disappear while the camera is on Lionel and reappear when back on Lex. This happens after Lionel turns to face slightly behind Lex and continues throughout the rest of that exchange.
Skinwalker - S2-E10
Continuity mistake: When the wolf jumps out the window of the Luthor mansion there is no blood on the glass shards that are left in the window. As Clark goes to the window, there is, all of a sudden, a lot of blood present on the glass.
Skinwalker - S2-E10
Continuity mistake: Joseph, Kyla and Clark are at the Talon, in the scene after Joseph is bailed out of jail. Martha comes in and walks over to the three of them. The next shot has her stopped next to Clark, with no forward movement to indicate she is still walking to him. In the shot after that she is still walking up to Clark.
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