But arguably, no one was left more in awe of what was accomplished than Gosling. Despite working with Stone twice before -- in 2011's "Crazy, Stupid, Love" and 2013's "Gangster Squad" -- the actor told CNN at Tuesday's Los Angeles premiere that Stone still found a way to surprise him with her skills.
"She shows so many of her talents in this film," he said. "I thought I knew they were there, but I didn't see them in full bloom until we shot the film."
One of Stone's shining moments in the film involves her character, an actress, attending a terrifying and vulnerable audition that could make or break her future. In the climactic scene, Stone performs a hauntingly beautiful tune that Stone admits was a tough one to get through.
"It was just a little overwhelming but in a great way," Stone said.
Gosling, too, deserves praise for his commitment to playing jazz musician Sebastian. He learned to play piano especially for the role in just a few months.
Director Damien Chazelle said it was a feat that could not have been pulled off by just any pair of actors.
"I think they do this incredible magic trick in the movie and make it seem effortless," he said. "It's hard to imagine anyone else pulling it off."
Gosling said he and Stone were always up for the challenge, however.
"There was always something challenging to do on this film," he said. "Anytime you had finished one number, there was something like next week you had to do that was equally as difficult, so we didn't really have a lot of chance to stop and get scared of any one particular moment, you know? We were in for the ride."
The film itself, too, is a journey, chronicling one year in the lives of the two characters as they fall in love in Los Angeles and individually pursue professional dreams.
Chazelle said he sees it as a story of hope and "I think that we need some hope right now."
Stone views the tale as a timeless story.
"I would hope that it's something that brings people some joy and a sense of being understood if they're dreamers or creative people in any way," she said. "It's a movie about dreamers and artists and how difficult it can be to realize those dreams and the joy of the journey."
"La La Land" opens in theaters December 9.