According to Mia Farrow, the scenes where Rosemary walks in front of traffic were spontaneous and genuine. Roman Polanski is reported to have told her that "nobody will hit a pregnant woman." The scene was successfully shot with Farrow walking into real traffic and Polanski following, operating the hand-held camera since he was the only one willing to do it.
Ira Levin felt that this film is "the single most faithful adaptation of a novel ever to come out of Hollywood." William Castle speculated the reasons for this were because it was the first time Roman Polanski had ever adapted another writer's work, unaware he had the freedom to improvise on the book.
Roman Polanski said working with John Cassavetes was not his "best experience. John was not very comfortable with the role". According to Mia Farrow, Cassavetes resented Polanski's highly structured method of shooting scenes, saying he preferred to improvise and a more freewheeling approach. Eventually the tensions grew between the two because of their conflicting approaches to film. In an interview featured on the Criterion Collection Polanski said Cassavetes was a "pain in the a____".