Visible crew/equipment: When Clark finds Lex in the Luthor mansion, they walk down the hall and into a new room. As they enter, as Lex is saying "So, hows the new ride?" if you look in the bottom left of the screen you can see a white tape marker on the floor, where Lex will walk over to subsequently. (00:33:10)
Audio problem: Clark listens to his father and Earl talking in the hospital through the visitor window. The sound is the same volume and quality as when Earl was using the microphone, which he is not using now. Even if Clark used super-hearing to eavesdrop, it wouldn't sound the same as the microphone. (00:18:35)
Deliberate mistake: Clark's CPR form is terrible. When he performs emergency breaths on Lex, Lex's chest doesn't rise and fall, indicating that he's not actually breathing much air in. He doesn't bother to measure for the proper location for chest compressions, a very important step that is the difference between proper CPR and simply cracking ribs. As he performs compressions, he is not chanting the rhythm (one-and-two-and-three) and his elbows are bent. All of these were altered for dramatic reasons or the purpose of safety, but the sloppy technique probably would have killed Lex. (00:18:40)
Audio problem: When Mr. Luthor was buying the corn field from the farmer he says: 'Now, where do I sign?' The farmer replies: 'Right here Mr. Luthor' and points at the contract. Even though we can only see a profile shot of the farmer as he says these words it is pretty obvious that his mouth isn't moving.