Around 38 minutes into the film Mandie and Polly are exploring the house. As they reach the stairs Mandie has a back pack on, as they climb the stairs she doesn't have it on but when they get to the top she has it on again.
When Zach arrives at the mansion, he's covered with cat hair, but immediately after coming inside, it's instantly gone from his clothing.
40 minutes or so in Mandie hands the Lamp to Polly who holds her hand over the glass, if it were a real lamp she would have burnt her hand.