Rosamund Pike and Neil Patrick Harris shot their 'Gone Girl' sex scene, in which his character gets his throat slit, 36 times.
The 35-year-old actress and the 41-year-old star - who played Amy Dunne and Desi Collings in the thriller movie - had 450 gallons of blood, 36 pairs of underwear and 36 sheets on hand as they filmed the violent footage, in which Rosamund's character slit's Neil's alter-ego's throat.
Director David Fincher told Vanity Fair magazine: "I told them to rehearse it for three days, as we're pumping five gallons of blood out of Desi's throat."
As well as spending hours just on one scene, Rosamund - who gave birth to her second child with long-term partner Robie Uniacke last month - believes she appears on screen more in 'Gone Girl' than the rest of her film career put together because of the movie's big filming schedule.
She said: "I spent more time in front of the camera on that film than in my entire career to date, because he's [Fincher] shooting five to six hours of footage a day, and over a hundred days shooting -that mounts up."
Despite spending a lot of time on the big screen last year, Rosamund likes to remain as private as possible about her personal life, rarely speaking about her partner Robie, but she does point out that one of his major qualities is that he is not fame-obsessed.
She added: "The quality I most admire about him is he sees the value in anonymity."
The full interview with Rosamund can be read in the February issue of Vanity Fair magazine.