The 53-year-old actress was photographed on the Los Angeles set alongside her co-star Javier Bardem, who portrays Desi Arnaz and many fans took to social media to share their displeasure with Kidman’s casting as the "I Love Lucy" star.
"They are so wrong for the parts! I don't get this casting choice," wrote one person who commented on Instagram photos published by Just Jared, while another added, "I love her but she looks nothing like Lucy."
"Literally everyone else in the world looks more like lucille ball," added a fan who responded to an image of Kidman posted to Twitter.
Other fans even suggested "Will & Grace" star Debra Messing would have been a better option to portray the studio executive instead of Kidman.
"Debra Messing should be Lucille Ball," wrote one commenter on Instagram, adding, "Brutal casting. Nicole has zero sense of humour."
Many others said the casting doesn’t matter as long as Kidman’s performance remained on point in the film about the pair’s turbulent marriage.
"I mean, Nicole Kidman doesn't have to look like Lucille Ball for her to do a good job in this role," said one fan. "And there's really no reason to pretend they look alike."
"I’m really excited about this!" wrote another fan. "They look good."
In February, director Aaron Sorkin defended the film's casting in an interview with Entertainment Tonight, telling fans not to worry until the final on-screen product.
"I think that the people thought that we've cast them as Lucy and Ricky Ricardo," Sorkin said. "The film takes place during a production week of 'I Love Lucy' — a Monday table read to Friday audience taping, with a whole bunch of long flashbacks which are telling the story that got us here — and because there's a table read, there are rehearsals and then there's tape night, we do see moments of them being Lucy and Ricky Ricardo."
"We see moments from an episode of 'I Love Lucy'. But mostly they are playing Desi Arnaz and Lucille Ball. And they're going to be fantastic...These are two of the greatest actors ever," he added.