When Marie determines chemical composition of pitchblende, 7 minerals add to 99%, one mineral (magnesium oxide) is .99% and the "extraneous matter" of .001% all adds up to 99.991%. Presumably the mag-Ox should be .999%, otherwise, the actual extraneous matter would be 10 times greater (.01%) than Marie's stated measurement.
After Pierre's street accident, when the men come to tell Marie, she comes into the hallway and puts her hand on the dowel of the railing; in the next shot, her hand is down, and she puts it up on the dowel again.
On New Year's Eve, Pierre and Marie try to stay awake all night in an attempt to crystallize radium. At some point, they decide to take a nap. When Marie awakens, she asks Pierre the time and he says it is 5:00AM. In their laboratory, there is full daylight and one can see sunlight appearing through the windows. At the beginning of January in Paris, the sun does not rise by 5:00AM and thus, the room should have still been dark.
Throughout the film Marie Curie is referred to as a blonde, but Greer Garson was naturally red-headed and no attempt was made to lighten her hair to make her look blonde. Her hair photographed the dark grey common to redheads in black-and-white films of this vintage.