The actress stars as the Evil Queen in the fantasy comedy and was often weighed down by her elaborate regal dresses.
One bronze-coloured outfit, which she wears while sitting on her throne in the film, weighed a hefty 60 pounds (27.2 kilograms) and Roberts admits she had to get ready for the shot in a specially-erected tent.
During an interview with U.S. talk show host Ellen DeGeneres, she said, "I had a tent on the stage that I went in to dress because that dress doesn't go into any modern doorway and that dress weighed, I think, 60 pounds."
And the heavy material even left Roberts with an injury after filming scenes with co-star Nathan Lane.
She added, "I actually pulled a thigh muscle trying to chastise Nathan, turning really quickly."