Comic-Con 2013: Sandra Bullock, Playing Astronaut in ‘Gravity,’ Admits Fear of Flying

Comic-Con 2013: Sandra Bullock, Playing Astronaut in 'Gravity,' Admits Fear of Flying

The movie was supposed to take one year. It's taken five.

There was just one problem when Sandra Bullock agreed to star with George Clooney in "Gravity," Alfonso Cuaron's film about two people stranded in space: Bullock is afraid of flying.

One other hiccup: she's claustrophobic.

Bullock revealed her private phobias to an appreciative Comic-Con audience in Hall H on Saturday, where Warner Bros. showed an exclusive, stunning sequence of the film.

Clooney and Bullock battle the destruction of their ship in deep space. Though the movie will be released in 3D, they did not show the clip in that format.

Cuaron, who criticized the flaws and excessive use of 3D on Thursday, first pitched the movie as a "space suspense in 3D" — back when it was cool.

That was almost five years ago.

When Alfonso Cuaron first finished writing the script, he promised cinematographer Emmanuel “Chivo” Lubezki they would finish it in one year. The film had just two main characters and a simple premise.

“We can shoot it in one year and we're out,” Cuaron recalled telling Lubezki, with whom he worked on movies such as “Y Tu Mana Tambien” and “Children of Men.”

Also read: Comic-Con 2013: 'Game of Thrones' Kit Harington Joins 'How to Train Your Dragon 2'

Cuaron then spent years trying to figure out how to shoot the film, which required recreating zero gravity for extended takes that show a space station blowing to pieces and the astronauts struggling to survive.

“For next 4 ½ years [Lubezki] kept on reminding me of that,” Cuaron joked alongside directors Marc Webb and Edgar Wright during a Thursday panel dubbed "The Visionaries."

The Mexican filmmaker soon discovered that no technology could replicate an environment of zero gravity – where two people float and spin on different axes.

“That doesn't happen on planet Earth,” Cuaron said.

Eager to make the movie anyways, he tried a variety of approaches, including the Vomit Comet — a ship that ascends to the stratosphere and then free falls for 30 seconds. 

That was news to Bullock, who found out just two weeks before shooting.

Though Ron Howard used it in “Apollo 13,” Cuaron eventually decided it wouldn't work for his film because the characters don't float. They fall.

“It's so much fun, but the problem is you're limited to the space of the place and it lasts for only 20 seconds,” Cuaron said.

See video: George Clooney, Sandra Bullock Enjoy a Beautiful Sunrise in First 'Gravity' Trailer (Video)

Cuaron has a predilection for long takes, so he and his team used different technologies for different segments, includng one that placed Bullock in a nine-by-nine cube where everything around her moved and she was static. All of the segments shared one common element – they were very painful.

“It's been an amazing miscalculation,” Cuaron said. “It was supposed to be ready last November and was not ready. I haven't finished it yet. One day I'll finish it.”

“Gravity,” whether Cuaron is ready or not, is scheduled to come out this fall.