Revealing mistake: In the scene in which Jonathan shoots Lex, he is gently lowering and raising the barrel of the gun whilst shooting, even though there is a 'bullet-time' effect in progress. Maybe the sequence is shot in real-time, with the actors standing still and the 'bullet' added afterwards? Furthermore, would Lex really move that quickly in relation to the speed of the bullet?
Continuity mistake: When Martha Kent and Lana were talking about the meteor shower in the Talon Relief Center they sit down on the stairs. Lana puts both her hands on her knees. But in the next shot now her arms are outstretched in front of her, and now it's her elbows which are on her knees.
Continuity mistake: When Clark lifts Lana back onto the bridge, from a shot from above, we see that Lana puts her left leg onto the bridge into a sitting position. They then cut to a different angle but now both her legs are still dangling and she eventually puts her right leg on the bridge first.
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)Phoenix
Continuity mistake: There are several close up shots of the syringe that Dr. Hamilton is using to threaten Pete with and you can see that it is made of plastic. Clark uses his heat vision to overheat the syringe causing it to burst but the sound the syringe makes when it bursts is that of a glass syringe and not the plastic one he was actually using.
Continuity mistake: When Clark, Pete and Chloe were looking for Clark's father in the woods, Pete says: 'the twister must have dropped it here' and we see Chloe holding the map in her right hand. Cut to a different angle (as Clark runs towards the screen) and in the background we see Chloe holding the map with her left hand instead.
Revealing mistake: As Sheriff Ethan pulls up there is a reflection on his driver side window. You can see the police department shield on the door and the door handle reflected on the driver's side window. There were no other police cars there so it was probably reflected off a mirror used to help light the scene.
Continuity mistake: After the credit card company calls the Kent's to confirm purchases made the night before, we see Jonathan holding a mug by the rim. They then notice the music coming from Clark's barn and go to investigate. Cut to a different and now Jonathan is holding the mug by its ear.
Plot hole: When Nixon and Jonathan are trapped in the crypt after the landslide, Nixon says he can't breathe, and Jonathan says this is because the landslide cut off the air supply. However, we can see beams of sunlight shining in. So, unless the ceiling of the crypt is made of airtight glass, that landslide didn't cut off the entire air supply.
Continuity mistake: When Clark is fighting with Dr. Walden, twice Dr. Walden sends Clark flying, with his powers. Both times, when Clark hits the ground, he becomes quite buried into the soft dirt, not entirely, but relatively sunken into it. However when it will cut to the next shot, Clark is lying on the dirt without being buried into it at all. This is obviously due to switches between actor and stunt double.
Continuity mistake: At Ryan's surprise welcome back party, Clark puts his right hand over Ryan's shoulder as he asks him "you knew about this didn't you?" Cut to a different angle as Ryan responds "I was tempted too" but now Clark's hand is no longer on Ryan's shoulder. Cut to Clark then back to Ryan and now Clark's hand is back on Ryan's shoulder.
Continuity mistake: When Lana was making a video to send to Whitney, we see her interviewing Clark. We first see Clark through the camera's view finder. Lana then drops the camera (pointing it down) such that we see Clark's feet. Cut to a different angle but now Lana's is pointing the camera at Clark's chest level.