Continuity mistake: When Pete and Clark go to Byron's house to find him, Clark finds the hidden locked door to the cellar. Clark then breaks the locks and uses both his hands to pull on the door. Cut to a different angle (from above Clark) but now he is just using his left hand.
Continuity mistake: After Byron transforms, he pushes Pete through the windshield of an old car. The impact causes the front passenger door of the car to open. Yet later when Clark check up on Pete, the front passenger door is now closed.
Continuity mistake: After Clark reads Lana's letter that she found, Pete gets up and sits on the couch next to Chloe. When Clark says "Sounds more like a stalker than a secret admirer." a shot of Pete has him sitting back over by Clark even though he was over by Chloe.
Continuity mistake: Byron mom buys him a book by Edgar Allan Poe at the used bookstore. Byron takes it with his right hand and looks at it. Cut to a wider angle (as Byron stands up) but now he is holding the book in his left hand.