Continuity mistake: Shortly after their cell phone conversation, Lionel sees Lana and gets out of his car. In the next shots of Lionel, his car has moved position from behind him.
Continuity mistake: Clark has to save Lana from a bomb as she is unconscious next to it inside a warehouse. As the bomb explodes and Clark runs through the fire to rescue Lana in the overhead shot she is on her side. In the next she is on her back.
Revealing mistake: After everything with Dawn is over Clark goes back to the prom. Clark asks Lois if she wants to dance. Lois says "I'm not the one you want to dance with." and she nods to the door. The shot switches to show Lana walking in to the prom. When Lois makes her nod to the door Lana would have been completely out of sight. Lois nods before Lana even enters the room.
Suggested correction: We never see Lana walking into the gym. She's just standing at the door, nervous about going in. We don't know how long she was standing there. Not to mention the fact that the scene of Lana at the door could have happened at the time Lois was making her comment and Lana walked in before the first time we see Lois look at the door, before she nods.
Continuity mistake: In the head on shot of the car that almost hits Mr. Altman you see the driver of that car react by turning his car to the left. In the very next shot, as Clark and Mr. Altman are just coming to a stop after Clark's high speed rescue, the driver is now turning his car to the right, as shown by which way his wheels are turned.
Continuity mistake: When Adam says "It's nice to be appreciated" Lex is looking at Adam. In the next shot, as Lex says "strange thing is." and now Lex is looking down at the file or piano.
Continuity mistake: Lex brings some comic books to Ryan at the hospital. He holds all of them with his left hand. He then shows 66 of the comic to Ryan and holds it with both hands. Cut to a different angle and now he is holding the comics with just his left hand once again.
Continuity mistake: After Lionel finds out about the wire that Lex has been wearing, he sits down and tells Lex to get out. As Lex leaves, in the wide shot, Lionel drops his hands down to his lap. In the zoomed in shot Lionel's hands are up to his face as he plays with the wire. There was no time for him to make that move between shots.
Continuity mistake: Lionel press conference about Lex's kidnapping only infuriates Rachel. She then picks up an axe and was about to swing at the tied up Lex when he manages to get his right leg free and kick Rachel backwards. As she falls backwards, we can see that she drops the axe off to her left side. Cut to a different angle but now the axe is over her head to her right side.
Continuity mistake: While in the line to claim their class rings, Pete holds a folded piece of paper (probably his receipt). As Clark says: "I earned that money.", Pete starts to unfold the paper. Cut to a different angle as Clark continues: "Besides, my dad said." but now Pete is looking at a completely unfolded piece of paper.
Revealing mistake: In the Talon when Crissy is talking to Clark, we see a close up of her hand aging. However, as her hand ages, a reflection of her real hand (which supposedly aged) can be seen on the metal clip of her clipboard, which is still young and smooth, and not aged.
Continuity mistake: When Kyle goes to confront Rickman about coming to Smallville, Kyle is talking about how Rickman agreed not to do anything in Smallville and Kyle is pointing with his left hand. When the shot switches he is now pointing with his right.
Exodus (2) - S2-E23
Audio problem: At the wedding, after Jonathon gives Lex the compass, in a side shot we hear Jonathon say a line, yet his mouth is completely out of sync.
Continuity mistake: As Clark is sitting in his barn's loft his mother enters while he watches a model of the solar system. In the shot when he turns it off the large red globe, which looks to be Jupiter, stops well to the right of the model's sun in this shot. When the shot returns to Clark, Jupiter is now partially in front of the sun. Clark had not moved his hand from the off switch so he didn't move the model by hand and the model would have taken longer to make another rotation to put in that position.
Continuity mistake: As Lana gets ready to throw the first ball there is a kid in a red, black and white shirt in the background and he is walking away from the scene. Just after she throws the ball the very same kid is calmly walking behind her again.
Factual error: Perry uses a simple black rope to tie himself to the railing by his ankle. This is not a bungee cord of any kind. He falls and is stopped, jerked to a stop actually, with both his weight and the weight of Clark pulling on his ankle. This would cause a very serious sprain if not an actual broken ankle yet Perry shows no signs of being injured when he and Clark walk to the bus.
Continuity mistake: When Lana and Clark are sitting on top of the windmill, Clark's jacket changes from opened to closed to opened.
Factual error: Tate fires at Clark, who is dressed as the drifter, 8-9 times from a revolver that is chambered for only 6 rounds.
Suggested correction: I count 5 shots fired, which is how he had 1 left that he was planning on using on himself. You must be counting ricochets or other sounds as shots fired.
Continuity mistake: When Molly first starts flipping through the disks for Lex, she has a ring on her left ring finger. After Lex talks about just getting back Molly is shown still flipping through the disks only now the ring is gone.
Insurgence - S2-E12
Continuity mistake: When Lex speaks with the Lieutenant, watch Clark and Jonathan in the background. They are seen standing by a News Now van and looking up at the Daily Planet. When the camera cuts to them, they are shown walking past the News Now van again.