"For Falconetti, the performance was an ordeal. Legends from the set tell of Dreyer forcing her to kneel painfully on stone and then wipe all expression from her face—so that the viewer would read suppressed or inner pain. He filmed the same shots again and again, hoping that in the editing room he could find exactly the right nuance in her facial expression."
In their biography of Dreyer, however, Jean and Dale Drum say that these stories are based only on rumour and that "there is no evidence that Dreyer could be called a sadist". They quote onlookers who described Dreyer's working relationship with Falconetti: initially in the production process, "Dreyer and Falconetti would watch the rushes of a single scene together, seven or eight times, until Dreyer could pick out a little bit, maybe a few feet, where the effect was what they wanted, and when they reshot the scene, she could play it without the least inhibition. Just those few feet of film had inspired her." Later, Falconetti became able to play scenes only from Dreyer's explanations, without the need even for rehearsal
Missing Episode: Very narrowly averted. The original negative was destroyed in a fire in 1927, and Dreyer died in 1968 thinking it was lost forever. While several copies of the film did exist, these had been subjected to government or church censorship and heavily recut as a result. Fast forward to 1981, when a nearly pristine copy of Dreyer's own final cut was discovered in a closet in a Norwegian insane asylum of all places. What's more, it was delicate nitrate stock in a sealed can; if whoever discovered it had opened it up when they found it instead of calling in experts, it likely would have literally gone up in smoke then and there.