The filmmakers used the original play as the screenplay and, aside from toning down some of the profanity slightly—Martha's "Screw you!" (which, in the 2005 Broadway revival, is "Fuck you!") becomes "God damn you!
The film adaptation took the original stage work as its basis and made subtle changes to reduce the strong language—Martha's angry outburst ('Screw you!') was softened to 'God damn you!' in the movie version.