Clark claims that all the documentation in his Kryptonian ship was in a language he couldn't understand. This directly contradicts the previous episodes "Foundling" and "Big Girls Don't Fly" in which not only Clark, but Earth natives Lex Luthor, Nigel St. John, Jack, and Lois Lane all are able to understand the documentation left on the ship. Moreover, throughout this story arc the Kryptonians encounter no language barrier when communicating with humans.
You can clearly see the wire lowering Superman when he arrives in Metropolis to do battle with Lord Nor.
Colonel Cash had the kryptonite all along but said he needed Superman as bait to get Lord Nor to Metropolis so that he could kill him with the kryptonite gas. However the day before Lord Nor AND all his followers/army attacked Metropolis before Superman even got there and Colonel Cash could have used the kryptonite gas on them without putting Superman in danger.