American Sniper,” written by Jason Hall and directed by Clint Eastwood, had a 44-day shooting schedule on a budget of nearly $60 million. The Warner Bros. film, in association with Village Roadshow, earned six Oscar nominations, and has taken in close to $300 million at the worldwide B.O. so far.

The sequence: Much has been made of the nail-biting tension of the opening scene, where Chris Kyle (Bradley Cooper), his finger on the trigger, must decide whether to kill a woman and a boy who may or may not be suicide bombers. But another scene in the film packs an equal emotional wallop. Kyle, in Iraq, along with members of his SEAL team, is being shot at by a sniper named Mustafa as they try to save a boy being held at gunpoint by an al-Qaeda operative known as the Butcher. The action starts when Kyle is in the middle of a phone conversation with his pregnant wife Taya (Sienna Miller) in the U.S., who’s just told him they’re going to have a son.

The challenge: The five-minute sequence is chaotic, involving principals, extras, stuntmen, two Humvees, a dog and lots of gunfire. There were at least 150 camera setups in three days to convey the multiple storylines as Kyle tries to keep one foot in home life and one at work — balancing the news that he’s having a son while fighting for his life.

The location: Rabat, Morocco. Eastwood brought in about 150 cast and crew  for 12 days of shooting. The director, producer Robert Lorenz and Charisse Cardenas (production designer for the war scenes) scoured the city to find a space to accommodate the sight lines, spatial relationships and choreography for the scene’s multiple POVs. They climbed many flights of stairs to find the right rooftops, and Cardenas’ team added war rubble to the town square.

Training: Whenever possible, the production hired people with military backgrounds to serve as extras, and put everyone through weapons training. Military advisers conducted two boot camps. James D. Dever was senior military technical adviser; cast member Kevin Lacz, a former SEAL, also handed out advice.

Meanwhile, back at the ranch: In contrast to war-zone photography was the small-scale filming of Taya leaving the medical center. The sequence requires Miller to react to the sounds of battle that Taya could hear via cellphone.

Sound: Sound mixer Alan Robert Murray was “a stickler, making sure each weapon had its unique sound,” Lorenz says. So after filming, Murray went to the location and re-recorded each weapon separately to replicate the distinct sounds of the rifles, automatic weapons and the 50-caliber guns on the Humvees. Later, the sound-mixing team added multiple layers, which also included the sound of the vehicles, explosions, a guard dog — and dialog.

Editing: The trick for editors Joel Cox and Gary Roach was to get the balance right as they intercut the military action with Taya’s reactions at home. They also had to delineate activity involving four different focuses: Kyle; Mustafa; the Butcher, the boy and his father; and the other military members, including SEALs, Marines and a CIA agent. The editors’ job was to make the action clear and the emotions strong. Once they assembled the sequence, they kept tightening it for impact.