Renée Zellweger spent a year training with vocal coach Eric Vetro before shooting began, then rehearsed with musical director Matt Dunkley for four months to master her vocals.
Before this, another biopic about Judy Garland was planned in 2009 that would have starred Anne Hathaway, but it was never produced. It would have been based on a biography by Gerald Clarke called "Get Happy: The Life of Judy Garland," and would have included Garland's experiences about being sexually harassed and abused by head of MGM Louis B. Mayer and other executives during her career. Ironically, the producer of the film would have been Harvey Weinstein.
Make-up designer Jeremy Woodhead had to prosthetically extend the tip of Renée Zellweger's nose slightly to better match Judy Garland's profile. Dark gray contact lenses were used to approximate Garland's dark brown eyes, and a cropped walnut-brown wig was fashioned to resemble Garland's iconic hairdo.
This movie was a loose adaptation of the Olivier-nominated play "End of the Rainbow". Playwright Peter Quilter said he believed screenwriter Tom Edge "wanted the story to be much more true and precise", with fewer "elements of fantasy" than the play.