Factual error: In one of his first appearances, Proulx the Architect is using a modern pen on a pad of paper when taking notes.

Revealing: The first time we see Madeleine's corpse in the chapel, under the white sheet, watch her chest closely: you can see her breathing.

Factual error: In the scene right after Madeleine tells the Marquis de Sade of the Doctor's marriage to the convent girl and the Marquis is writing a farce, the ink is blue, even though blue ink was not invented until post WWI 1900s.

Continuity: After Madeleine has been whipped and she is putting her clothes back on, she puts her arm into the same sleeve twice.

Revealing: When the Abbe du Coulmier comes running around the corner towards Marquis' cell during the fire scene, you can see him smash his head against the wall.

Plot hole: Despite being whipped and needing to go to the hospice afterwards to have her wounds seen to, when we see Madeleine later in the film she doesn't act as though she had whiplashes across her shoulders - she lies on her back that very night in bed, and gets up without a wince, she holds her shawl close when she is wandering around the asylum, she leans back against chairs, and in all the later scenes she is still wearing her tight bodice, despite the fact that such wounds would have been very painful for ages afterwards.

Continuity: In the Abbe's dream when he and Madeleine are making love, the position of their heads changes from being face to face in all the side shots, to side by side (so we can see Madeleine's face) in all the above shots. Madeleine's eyebrows also change, from having a kink in the left side one in several of the frontal shots, and to being smooth in all the side views.