Continuity mistake: When Clark is in the barn throwing footballs through the tire. He starts out with four footballs on the rack, but after he throws two, there's only one ball left.
Continuity mistake: When Lex finds Clark in the Talon doing his essay, he sits and talks with him. He puts his cup on the table and puts his hands in front of him. In the next shot, Lex now has his arms crossed in front of him on top of the table.
Audio problem: While Clark says "next time I could hurt you or mom." the camera is behind him. As he says "you or mom" his head is turned so that you can see his lips do not match the words being said.
Revealing mistake: When Lana has her nightmare, she wakes up in a room and discovers various people on pedestals, underneath body sheets. During the scene, some of the people under the sheets can be seen lightly breathing, although everyone under them is dead.
Continuity mistake: When Chloe finds Lois stabbed in the dam, we see Lois on the floor with her arm hanging so that her hand is right beside the stab wound. However in the next close up of the wound, her hand isn't there. It's back beside it in the next shot. (02:28:20)
Transference - S4-E6
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: When Victor is going into Lois' apartment with Clark and Lana, he is holding his jacket over his wound to soak up all the "blood". Later, when he goes to see his girlfriend, he is wearing his jacket, but his jacket has only a small stain now.
Continuity mistake: While Chloe and Lex struggle for control of the gun Simone puts both arms down to her side. The shot switches to a slow motion shot of Simone getting shot and instantly Simone has her hand on the jewel again.
Continuity mistake: Right after Ryan makes breakfast for the Kents, he leans on a chair and sets the orange juice jug down twice. (00:05:35)
Other mistake: Maddie and her father can control only glass, but when at the Talon he uses his powers to pull the diamonds out of the stained glass. Diamonds aren't glass.
Suggested correction: This may not necessarily be true by the way their powers work. Remember, diamonds are a form of rock that are clear. Glass is made from melted sand, which is a ground up type of rock that becomes clear. The similarities between diamonds and glass are enough that it is possible they could still do this.
Diamonds are compressed carbon, not a form of rock. Glass is melted silicon. They're both clear materials, that doesn't mean they're equivalent, otherwise they'd be able to control clear plastic or any number of other things too.
If more explanations of their powers were discussed in the show, one might be able to conclude they do or do not have power over diamonds. However, the script only states they have power over glass, they show no propensity for power over sand itself, or other rocks and minerals. As scripted, this remains as error as it go against what is established.
Factual error: When the bug kid crashes his car, he's driving a VW Beetle, which has the motor in the rear, therefore would not have shut off in a head on collision.
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. (00:28:00)
Continuity mistake: When Lana comes in with her brown bag of groceries, she puts the vegetables and wine bottle on the counter. During the rest of the scene these items move their positions a few times.
Factual error: In the scene where Clark stops Pete on the country road and is trying to talk Pete out of racing, mountains can be seen in the distance. There are no mountains that tall in Kansas. (00:09:55)
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.
Continuity mistake: During a fight, the thug rips off the bra that Oliver Queen is wearing, rendering him bare-chested. The following shot, taken from a different angle (from the back), shows Oliver still wearing the bra whilst punching said thug.
Visible crew/equipment: When Lex and Chloe are talking after the morgue, you can see a crewmember passing behind her at 30:53. (00:30:53)
Suggested correction: You see a person walk behind her in a corridor. Since it is very obvious and occurs during a short cut where nothing else is happening, it is deliberate. A fundamental rule on film sets is that once "action" is called, no-one moves if they don't have to. If a crew member had walked through the shot like that, they would have done a new take or just use a different segment of the shot.
