Factual error: Clark finds Lois in the sewer and decides to use his heat vision to destroy the lock of the gate that is separating them. Clark uses his heat vision on the lock and the lock explodes, this is a very minor explosion. It also causes the door to fly off the hinges. Now the explosion from the lock is odd since heat vision causes things to melt and not explode, but Clark wasn't even using the heat vision on the hinges and they are destroyed. This is inconsistent with how his heat vision has been shown to work before.
Continuity mistake: When Lex comes to after being kidnapped by Rachel, she wipes his face with a piece of cloth using her right hand. She then transfers the cloth to her left hand and continues to wipe Lex's face. Cut to a different angle as she says "I bought it with the money your father gave me" but now the cloth is instantaneously back in her right hand.
Continuity mistake: In the flashback when the Kent's meet Clark, we see Jonathan loading the space ship onto the back of the pick up truck. He then see Martha carrying Clark who was wrapped up in a blanket. At first we see that Martha's left arm is wrapped around Clark's back onto his shoulder. Cut to Jonathan's viewpoint and now Martha is just supporting Clark and her left arm is no longer around Clark.
Continuity mistake: At the Talon, Clark tries to write his essay when Crissy shows up asking Clark to sign up for the decorations committee. Crissy holds her clipboard with her left hand and places her right hand on her hip. But in the next shot Crissy's right hand on the clipboard as well. Cut back to the previous angle and her right hand is back on her hip.
Continuity mistake: As Justin turns the spike end of the pathway light towards Principal Kwan, in the close up, the light is at a height that is just lined up with the light in front of it. After the shot change, the shot simply zooms out to include Justin on the right side of the screen, the light is now several feet higher than it was before.
Continuity mistake: When Henry falls into the pond, the first time, there are several small pylons connected by a chain when the camera is on the walkway. When the camera is in the water, showing Henry as he hits the water, neither the pylons or the chain is visible. There is just an open space where the chair falls over.
Continuity mistake: When Lucas is in the Luthor mansion talking to Lionel and Lex, he picks up and inspects the samurai sword, then returns it to the holder, hanging it on one peg by the strap. In the next immediate shot, it is resting between the pegs, as it was before he picked it up.
Factual error: There is a snow pattern on the Quicktime player after Chloe's message to Clark finishes. She would have recorded in on a camcorder, so there wouldn't be any snow pattern, it would be a blue or black screen. The only way there could have been is if she recorded it, put it on VHS, then copied it back onto a DV tape, then transferred it back onto her computer, but there's no reason for her to do this.
Plot hole: Chloe has to use Lex's thumbprint to access the safe inside level 3. She gets his fingerprints by lifting it off of the flashlight he picked up for her earlier in the caves. The problem is when Lex picked up the flashlight and gave it to Chloe he had only touched the back half of the flashlight, but when Chloe lifts Lex's print she gets it from the opposite end. Since Lex did not touch that end there should be no fingerprints for her to lift and use on the security door.