There’s a scene in Last Tango in Paris where Marlon Brando’s character sexually assaulted Maria Schneider’s character using butter as a lubricant. This scene was allegedly not in the script, and she was only told about the addition right before it was filmed. In 2007, Schneider, who was 19 at the time of filming, stated, “During the scene, even though what Marlon was doing wasn’t real, I was crying real tears. I felt humiliated, and to be honest, I felt a little raped, both by Marlon and by [director Bernardo] Bertolucci. After the scene, Marlon didn’t console me or apologize. Thankfully, there was just one take.”

Source: https://www.buzzfeed.com/jonathansim/directors-going-too-far-on-movie-sets