There are two picnics in Gerwig’s Little Women: a wedding picnic and a beach picnic.
The first is Meg March and Mr. Brook’s reception. As in Alcott’s novel, it’s “a plentiful lunch of cake and fruit, dressed in flowers.” But Gerwig’s foods include wine, lemonade, and coffee. The happiness is marred only by Aunt March’s predictable sourness. “Well, I hope you’re happy. Now that you’ve ruined your life,” she says, “just like your Mother did by marrying your father.” 
Gerwig’s other picnic at the beach conflates two picnics in the novel; Laurie’s very successful gathering (at which Jo makes coffee), and a second, Amy’s fête that’s ruined when only one friend shows. * (See entry for Alcott.)
According to Gerwig, Jo remembers the beach picnic with brilliant clarity as it happened seven years before in 1862. She was a teenager then, but now as a young adult, she remembers it with joy and sadness. Jo remembers kite-flying, badminton, running, and playful jostling along the water’s edge. She remembers Amy showing her spunk by briefly flirting with Laurie’s English friend Fred Vaughn. More sharply, she recalled that when Laurie pairs off with her, she rejects his attempts at courtship.
Laurie: You’ll feel better about it when somebody comes to take you away.
Jo: I’d like to see anyone try it.
Miffed, Laurie turns and walks away. Neither he nor Jo looks back.
Returning to the present, Jo reads a somber passage from Elliot’s The Mill on the Floss: “We could never have loved the earth so well if we had had no childhood in it if it were not the earth where the same flowers come up again every spring that we used to gather with our tiny fingers.” When Beth asks why she has stopped writing her own stories, Jo (always a bit of a downer) is sad. “I don’t have any new stories,” she says. 
The cast: Saoirse Ronan as Jo March; Emma Watson as Meg March; Florence Pugh as Amy March; Timothée Chalamet as Laurie Eliza Scanlen as Beth March; Laura Dern as Marmee March; Meryl Streep as Aunt March; Tracy Letts Bob Odenkirk
Featured Image: With picnic baskets in hand, Beth, Amy, J, and Meg stand ready for their picnic at the beach.
See Greta Gerwig. Little Women (2019). Screenplay by Greta Gerwig based on Alcott’s Little Women, or Meg, Jo, Beth, and Amy (1869. There are eight film adaptations of Alcott’s novel, only Gerwig (to my knowledge) includes the picnic espsode:1917 Lost; 1918 William A. Brady Lost; 1933 Cukor; 1949 Mervyn LeRoy; 1970 BBC production; 1994 Gillian Armstrong; 1998 Masterpiece Theater
Streaming: https://www.youtube.com/watch?v=4_x8QPCEZFk and https://www.youtube.com/watch?v=ah24WK609E4