When the police cars are rushing to the scene of Elliot Ganz' mansion, the squad cars are late 1960's models and have round flashing lights, buy by the time they reach the scene, the cars are newer models with square flashing lights.
At about 17 minutes the Harts attempt to open a door & unable to open the the door they say it's closed but over Jonathan's shoulder the sign clearly says open.
When Jennifer is posing for the portrait, her face and body are angled to the right. The portrait shows her face straight forward and her body angled to the left.