Continuity mistake: During much of the conversation between Clark and Lana, while in the caves, you can see the cave painting that matches the tattoo on Lana's back is behind her. Then, towards the end of the conversation, she is still standing in front of Clark and during the scene has not moved from that position yet, once she sees the cave painting behind Clark she walks over to it and turns around to face Clark, which puts the painting behind her even though it was already behind her before she moved.
Revealing mistake: In the sheriff's office, the door to the jail area has no lock plate on the wall.
Continuity mistake: When Clark's truck stops rolling over the hood is stuck open. As Clark pops up from the front seat the hood is down for the camera to get a shot of Clark.
Continuity mistake: As the computer says "Subject seeds exposed to radiation" there is a camera shot showing the temperature monitor in the lower right of the shot. In that shot the readout shows the temperature reading is close to 100% of maximum. Then, in the next shot as the scientist says ".absorption level: as expected" the temperature monitor is now close to 90% as we see it climb up to the 98% they were trying for.
Continuity mistake: Clark goes to see Lex about the dog. Lex, who was about to start a game of pool, breaks a fresh rack. Lex then goes to make his second shot from near the side pocket and as he does you can see there are two striped balls near the rail close to Lex's cue stick. Just after he takes his shot those balls are gone even though those balls had not been hit.
Revealing mistake: At the beginning of this episode Lana is supposedly naked. However, when she dives off of the pier, she is wearing a pair of red shorts.
Insurgence - S2-E12
Revealing mistake: After Lex's employee walks out of the office, Lex gets mad and throws most of the objects off his desk. Prior to this, we see a computer screen displaying something. When the objects go flying off and hit the wall, we see that it wasn't actually a computer screen but a prop that was made look like one. It was just the frame, a piece of paper that served as the display covered by clear plastic to make it look like an actual computer screen.
Continuity mistake: When Pete and Jonathan corner Clark in the cornfield, Pete opens a lead box containing green kryptonite to weaken Clark. The position of how Pete holds the lead box changes every cut. At first he is holding it with just his right hand, then just his left, then both his hands.
Continuity mistake: When Chloe tells Pete about her discovery about the Red meteor rocks, she gives a sample to Pete who then looks at it. At this time the red meteor embedded in the rock is above Pete's left index and middle fingers. Cut to a close up of Pete's ring and the rock but now the rock is embedded in between Pete's left index finger and thumb.
Continuity mistake: As Chloe leaves Clark calls out her name. In the shot from Chloe's side of the room, Clark is holding the pitchfork horizontally low in front of him. The shot switches, as Chloe finishes her turn, and now Clark is holding the pitchfork with his arm bent so that the pitchfork is no longer low in front of his waist.
Other mistake: When the Marine officer comes to Whitneys house, he introduces himself as Lt. McNulty, but he is wearing the insignia of a Captain.
Audio problem: When Clark and Manhunter are in his Barn talking about how to stop Bizarro and figuring out the yellow sun can heal Clark, there is a beep of a watch or someting similar in the background, but neither Clark nor the Manhunter react to it, which means it happened off screen and unintentionally.
Continuity mistake: Alicia's hair keeps changing as Clark holds her in his arms. In some shots the hair on her right side is messy. When the shot switches to a close up, her hair becomes neatly combed and tucked behind her ear. All of this occurs after Clark burns the rope she was hanging by.
Revealing mistake: When Jason breaks into the bathroom to rescue Lana we see a shot of the shower from Jason's POV. In that shot you can see the steam is coming from the other side of the tub and is flowing up and in. If it had been actual steam it would go from inside the tub out.
Continuity mistake: After Clark gets his powers back the cut on his cheek heals and leaves only blood on his cheek. While still at the power generator he goes to wipe this blood off of his face with the back of his hand only in the shot just before you see his hand go to wipe, a second before his hand actually appears on screen, the blood that was on his cheek is now gone as if it was already cleaned.
Continuity mistake: As Lana starts her second swing at Chloe with the axe while the camera is in front of Lana Chloe is just barely getting up and is still close to the floor. The camera switches in mid-swing and suddenly Chloe is completely standing and is able to jump back to dodge the swing.
Continuity mistake: When Chloe and Jimmy find Lana shot in the elevator, there is a gun on the floor beside her, with a small pool of blood beside in the gun. In the next closeup shot on the floor, the small pool of blood is gone. (00:42:00)
Continuity mistake: The raindrops on Clark's shirt disappear and reappear between shots. Clark's shirt is dry when he turns to Chloe and asks "I'm not normal?" but before and after this his shirt has raindrops on it. This happens again a few moments later as Lois starts to talk about "panicking in times of crisis", Clark turns towards Lois and his shirt is dry.
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