Continuity mistake: Glen Holland owns a Chevy Corvair throughout the film. The car at the beginning of the film is a 1961 model 500 (the base model with bench seats), but at the end of the film it is a 1964 Monza (the top of the line model, with bucket seats).
Continuity mistake: When Mari gets up from the chair to go put the Nutcracker away, she walks towards a china cabinet. You can see by the shapes of the items through the windows in the doors of the cabinet that it is full of various dishes. But when she opens it, it is suddenly full of dolls and doll accessories.