Marilyn Monroe and Sir Laurence Olivier had trouble filming together. He would often get angry at her forgetting lines or being late to the set. Monroe was furious one day while filming, when Laurence told her to "just be sexy".
Marilyn Monroe got one-up on Sir Laurence Olivier after she discovered that someone in the crew (She suspected it was Olivier.) was running a book on how many takes she would need for a fairly tricky scene. She went home and studied hard, so that on the day of shooting, she was more than prepared. She delivered the line and then left the room, closing the door behind her as directed. However, within a few seconds, the door flew open again and Monroe stuck her head through the gap. "Pretty good, huh?" she exclaimed, before shutting the door for a final time. This line was not in the script and was an obvious dig at those who doubted her ability to do the scene. However, it fit in so well that it wasn't re-shot and remains in the final cut.
Three or four different copies of Marilyn Monroe's white dress were made to accommodate her fluctuating weight. At the time, she was suffering from various illnesses which caused severe amounts of water retention. She also suffered a miscarriage during filming.
Marilyn Monroe reportedly received 75% of the profits, such was the deal set up with her own production company.