Corrected entry: Jor-El tells Clark that he has to return to the Fortress by sundown or face the consequences. Later, Lex tells Chloe that they're in the Yukon, implying that the Fortress of Solitude is in the Arctic. Since the events of this episode take place in the summer, Clark should have had plenty of time to help out in Smallville - the Arctic enjoys permanent daylight during the summer.
Corrected entry: After Clark fails to prevent the death of Lana he is emotionally devastated and in a highly distraught state wanting only to be close to her as Jonathan pulls Clark away. Given Clark's emotional state and superior strength he would have been able to easily resist this action.
Corrected entry: When Professor Milton Fine/Brainiac tries to stab Clark with the crystal while they are fighting in the Fortress of Solitude, Brainiac is holding the crystal in his left hand. But when we next see the crystal after Brainiac is impaled, the crystal is in his right hand.
Corrected entry: Near the beginning of the episode Clark makes a diamond by squeezing a piece of coal with his super-strength and the diamond emerges as a beautifully cut and faceted gem. Diamonds have long been considered to be one of the hardest properties on earth and even with super-strength, could not be honed to this degree by bare hands alone.