Jane Fonda was in the audience Sunday at a preview of “I’ll Eat You Last,” and got to hear a dig at her expense in the Bette Midler Broadway show about agent Sue Mengers. The one-woman play includes a scene in which Mengers’ client Faye Dunaway is up against Fonda to star in the 1974 movie “Chinatown.” The show imagines a heated conversation between Mengers and producer Robert Evans, in which Evans said Dunaway has a reputation for being “hard to work with.” Midler as Mengers shoots back about Fonda, “What?! Compared to Hanoi Jane and her legions of protesting vets? Come on!” After the show, Fonda jokingly tweeted, “The stories [Midler] tells — to salivate over! Even though I’m the brunt of one.” Meanwhile, Midler’s still warming to the role before the show officially opens April 24: In a performance last week, spies said, she “forgot her lines several times” and had to be prompted. A rep explained, “The format is new to Bette, with changes being made to the script during the normal preview process.”