'La La Land' dance coach on Gosling's Oscars giggles

It earned six Oscars on its way to stealing hearts worldwide and grossing $440 million, but "La La Land" is perhaps doomed to be remembered for the prize it didn't win.

Director Damien Chazelle and his team hugged as they picked up best picture at February's Academy Awards, but it quickly became clear that the wrong movie had been announced.

As one of the worst mix-ups in Oscars history played out live to the world, the media noted one unusual reaction among a sea of perplexed faces: Ryan Gosling was struggling to control his laughter.

The star's giggles quickly went viral and he has since put it down to delight for the cast and crew of real winner "Moonlight," and relief that the sudden panic wasn't caused by something more serious.

But celebrated choreographer Mandy Moore, who taught Gosling and co-star Emma Stone to dance for the movie, thinks he was just embarrassed.

"Ryan's very like that -- he giggles at awkward moments -- so I think you see him giggling but that's just kind of how he deals with awkward things," she told AFP.

Moore, 41, has four Emmy nominations for reality show "So You Think You Can Dance" and choreographed routines for "Silver Linings Playbook," "American Hustle" and "Joy," but had never attended the Oscars.

She recalls sensing something was odd as presenters Warren Beatty and Faye Dunaway -- who it later transpired were holding the wrong card -- dithered onstage over announcing the winner.

- Breaking hearts -

"I was like, 'This is kind of weird -- or maybe they're being dramatic.' And then, when they said 'La La Land,' of course everyone's like 'Wooooaaaaaah!' Everyone's crazy and everyone starts to stand up," she told AFP.

The penny dropped before she had made it to the front, as she saw stage manager Gary Natoli appear before the crowd at Hollywood's Dolby Digital Theatre.

"The stage manager's not going to walk on unless there's a massive mix-up so I immediately was like 'okay, I'm going to go back to my seat,'" Moore said.

"La La Land," a celebration of the musicals of Old Hollywood, tells the story of an aspiring actress and jazz pianist pursuing their dreams in modern-day Los Angeles, a city known for crushing hopes and breaking hearts.

Such is the movie's popularity in its hometown that Los Angeles Mayor Eric Garcetti has declared April 25 "La La Land Day" in honor of the home entertainment release.

The Blu-ray includes 10 bonus featurettes and an audio commentary in which Chazelle and composer Justin Hurwitz reveal the musical prologue almost ended up on the cutting-room floor.

The sweeping, ambitious chorus number set on a gridlocked ramp connecting two LA freeways involved 30 dancers, 100 extras, 60 vehicles and months of planning.

- Epic opening -

The crew had been given permission to shut down the busy thoroughfare for 48 hours during a heat wave in August 2015.

Chazelle and Hurwitz explain that many producers were against the scene, which delays the introduction of the two stars, and it was cut out before finally being streamlined and being allowed back in.

"Funnily enough, in the script it really wasn't much," recalls Moore, who directed her dancers from a hiding place under a car.

"It basically said they get out of cars and they sing and dance and that it needs to be pretty much the most epic opening to a film ever, so no pressure."

Gosling and Stone, neither of whom had any tap or ballroom dancing knowledge, were put through a grueling regime of hours of dance practice, Pilates, stretches and strength training.

"I knew that I had to build up their stamina because the duet in particular was a six-and-a-half-minute take where they were doing the scene and then they go into the song and then they dance," says Moore.

"It would have not been a good thing if one of them had been injured early on because they had so much physicality that they had to deal with through the film."