"The Swan" was written especially for this movie. The original number, "Rat-a-Tat-Tat", was deemed too dated (though appropriate for the setting of the show).
Frank Sinatra was seriously considered for the role of Nicky Arnstein but Barbra Streisand vetoed this as she didn't like him.
Several co-stars publicly blasted Barbra Streisand and director William Wyler for much of their scenes being cut in favor of focusing almost entirely on Streisand.
The final musical number, "My Man", was filmed "live" both to maximize Barbra Streisand's dramatic rendition and because she hated the lip-syncing process.
Barbra Streisand was, at the time of the film's release, a voting member of AMPAS. When she found she was nominated, she, like any member nominated, voted for herself. If she hadn't, she wouldn't have tied with Katharine Hepburn for the year's Best Actress Oscar.
William Wyler was hired to replace Sidney Lumet as director. Lumet left the picture over differences with producer Ray Stark and star Barbra Streisand. Wyler originally declined the offer, because he was deaf in one ear and said he couldn't do a musical, but reconsidered after meeting Streisand.
Funny Girl opened at the Winter Garden Theater on March 26, 1964 and ran for 1348 performances. Barbra Streisand and Kay Medford reprise their roles in the movie.