Continuity mistake: After Clark gives Chloe the piece of paper with the list of cars that checked into the hotel, Chloe holds the paper in front of a folded up newspaper. Between shots, the newspaper turns the direction it faces. Then in the next shot, Chloe is only holding the piece of paper, and the newspaper that she was holding behind it has now disappeared.
Continuity mistake: After Clark saves Lex from the ring of fire we see the area that was burned by the fire. The candle that Shannon used to light the alcohol is no longer on the floor. Since the candle was in the fire it should be partially melted and there would be some evidence of it.