It is sometimes incorrectly stated that the producers were never able to get the rights to All About Eve and that consequently the musical was based only on the story The Wisdom of Eve by Mary Orr. In fact, the producers did get the rights to All About Eve. Not only was it credited in the playbill as one of the two sources, it was credited ahead of The Wisdom of Eve.
Although some elements of All About Eve were not used, perhaps in part because the rights to the screenplay were not obtained until fairly late in the writing process, there is nonetheless a great deal in the musical that is not in Mary Orr's original story and that is also not in the radio play she wrote soon after (and before All About Eve). She did add characters and plot elements to the radio play that were used in both the film and the musical, but still a comparison of all three sources with the musical reveals that the musical uses a great deal found only in the film.