Continuity mistake: When Vermeer picks out earrings for his wife to wear, he selects two pearl earrings (same one later found on Griet). When he hands them to his wife, he gives them both to her, however when you look at Vermeer in the next shot he is holding one of the earrings.
Continuity mistake: Van Ruijven grabs Griet and makes her drop the plates she is holding. She bends down and picks up a broken piece of crockery and an unbroken plate. In the next shot, the plates she is holding are both unbroken.
When Griet is introduced to the camera obscura, far too much light is projected onto Vermeer's and Griet's faces. Camera obscuras don't make their own light; rather the image produced on the viewing screen is always dull.