Revealing mistake: As the helicopter that Lana is in dodges the falling meteors in mid-air, the camera shot focuses in on the cockpit. If you watch Lana's position as she first starts to appear she is semi-transparent and the frame of the window behind her is visible through her body.
Continuity mistake: During the scene when Jonathan comes home from the hospital the length of rolled up sleeve on Jonathan's left arm changes between shots. As Jonathan says "Low sodium turkey?" the sleeve is down to just about touch the watch he is wearing. When the camera jumps to Jonathan's left side, as Martha turns around, the sleeve is now several inches higher and further from his watch than it was before. Jonathan does nothing to his sleeve between shots.
Continuity mistake: At the bar, the agent looking for Jessie calls the barkeeper. He then proceeds to fold a piece of paper and puts down the pen which he was holding onto the bar. Cut to a different angle (as he takes out a photo of Jessie from his coat) but now the paper is unfolded and he is holding the pen in his hand again.
Continuity mistake: When Clark arrives late for school in Lex's car, he is stopped by principal Reynolds who tells him that he should have been there four minutes ago and points at his watch with his right hand. Cut to a different angle but now he is pointing at Clark with his right hand.
Continuity mistake: When the agent goes to the Luthor mansion and confronts Clark about Jessie's whereabouts, Clark uses his speed to push the billiard table into the agent and jams him against a wall. As he does, the billiard balls obviously move due to the force Clark put on the table. Cut to the agent and later on Clark and we still see the billiard balls on the table yet they are no longer moving. It was too quickly for an object in motion such as a billiard ball to come to a complete stop given the force Clark exerted on the table.
Continuity mistake: After Lex tells Martha that he'll do whatever he can to help Jonathan, she goes into Jonathan's hospital room. As she goes through the door, the blinds next to the door are closed. When the shot switches to show Clark standing at the other window, the blinds next to the door are open. Then, as Lex goes over to Clark, the blinds next to the door are closed again.
Continuity mistake: Pete arrives when Lana was interviewing Clark for a video that she would send to Whitney. Lana then asks Pete: 'want to give it a shot?' We then see Lana holding the view finder of the camera with her left thumb and index finger while the rest of her fingers in outstretched. Cut to a different angle (as we see Pete) but now the rest of her fingers are no longer outstretched.
Plot hole: Though it fits the general plot of Davis always being first on scene, in the real world no on-duty paramedic drives the ambulance alone. There will always be a minimum of two EMTs per ambulance, one to drive and one to tend the patient. The only time a paramedic or other EMT will be alone is if they arrived on the scene in their own vehicle.
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: While Martha reads to Jonathan, as he is in a coma, the light on his hands change. In the shot from the right side of Jonathan's bed his hands have only a normal level of light like from a small table lamp. The shot changes to look at Jonathan from the doctor's point of view and suddenly Jonathan's hands are very brightly lit like from a spotlight. No one changed or turned on any other lights between shots.
Continuity mistake: After Clark finds out that Ryan is dying, we see him holding a comic book in the farm. His dad then arrives and he turns to look at him. He places his left hand to his side as he holds the comic book in his right hand. Cut to a different angle and now both his hands are together in front of him.