Continuity mistake: Martha visits Lionel in prison not knowing Lionel is actually Clark. As she says "I'm only here because you told me it had to do with the safety of my son." the camera changes. Between changes, as Martha says "you", her left hand goes from being under the table to instantly being on top of the table.
Continuity mistake: At the bar, the agent shows the barkeeper a picture of Jessie. Throughout the whole conversation, it is the agent who is holding the picture. However, when the agent says something about the legal drinking age in Kansas, it is the bartender who is instantaneously holding the picture.
Continuity mistake: When Chloe and Clark are at the Torch after the pool incident with Shawn, Chloe is sitting down wrapped up in a green sweater and a blue jacket with part of her blouse showing. In the next shot, she is fully wrapped in the green sweater. Seconds later, her sweater is tucked into her jacket and her blouse is showing.
Continuity mistake: Clark rushes to get to school in Lex's car and we see principal Reynolds closing the gate to the school. In the close up, we see that the principal is off to the left of the lock of the gate. Cut to a different angle (his back to the camera) just as Clark arrives in Lex's car but now he is standing in front of the gate lock.
Plot hole: In this episode, Pete comes across Clark's spaceship in a field, where it landed after the tornadoes hit the town during the last episode of Season 1. The Kents knew the spaceship was gone, and of course it was important that they attempt to get it back as soon as possible so it doesn't fall into the wrong hands. With Clark's speed and x-ray vision, he should have been able to find the ship after not too long of a search (especially since it was within a few hundreds yards of a road). It seems implausible that he would not have looked for it, given its importance.