During the party when Corinne and her date are dancing, she is wearing a strapless dress and there are clearly no scars or any indication that she was beaten with a whip.
Near the beginning of the film, Chris walks in on Cathy in the bathtub. Her hair goes from long & dry to wet from one scene to the next.
When the grandmother deliberately knocks over Cathy's ballerina music box, she's wearing a green dress. The next shot, which shows her walking down the stairs, her dress is black. The latter scene was shot in Beverly Hills, California, the same time as the studio ending.
The kids are in the attic for months, but their hair never grows.
Cathy is wearing knee pads when she throws herself on the floor in an attempt to catch the ballerina figurine.
Very obvious wig on Cathy as she gets a haircut from Chris in the bathroom.