The Barbie producer called the filmmaker "one of the great directors of our generation".
Oppenheimer and Barbie open in cinemas on 21 July.
Hugh Grant was first seen as the Oompa Loompa in the film's trailer on Tuesday.
The trio joined previously announced stars David Corenswet and Rachel Brosnahan.
Dolittle's failure helped Robert Downey Jr. and his producer wife re-evaluate their priorities.
Greta Gerwig previously worked with Timothée Chalamet and Saoirse Ronan on Lady Bird and Little Women.
Margot Robbie explained why Greta Gerwig was the perfect person to write and direct the Barbie movie.
Michael Cera has revealed that he never joined the cast group chat because he doesn't own a smartphone.
John Boyega also felt confused when he watched the finished film.
Jennifer Lawrence felt so much confidence in the project.
Robin Wright described Bingo as a "modernized, beautiful" take on the May-December romance.
Chad Stahelski has revealed that he originally shot a "very clear" ending but they preferred the ambiguous one.
