When Maddalena disappears, she leaves a design on her mirror. Her husband sees it and exclaims, "The seven moons!" There are six.
When Tessa (Amy Veness) answers the door to Doctor Ackroyd (Reginald Tate), she takes his hat and gloves. She drops the gloves and spots that she's done so, but carries on with the scene.
When Madddalena's daughter returns from school, she is wearing a sport shirt, shorts--and high-heeled shoes, hardly a likely type of footwear for the outfit and occasion.
When the artist goes looking for a subject, he carries his easel and a canvas, but no paints.