Spike Lee’s Vietnam treasure-hunt adventure drama “Da 5 Bloods” serves not just as a tribute to greats such as “Apocalypse Now” and “The Treasure of the Sierra Madre,” but as an unexpected memorial to the power of Chadwick Boseman’s presence.

So said the Oscar-winning director and his cinematographer, Newton Thomas Sigel (“Bohemian Rhapsody,” “Three Kings”), in a live-streamed talk with Variety’s Jazz Tangcay at the EnergaCamerimage Film Festival on Sunday. The one-hour chat covered what the Vietnam experience meant for Black Americans in the midst of the civil rights movement of the 60s, how war can bond soldiers for life and the importance of including all perspectives.

“Black people are not just one monolithic thing,” Lee said, recalling his mother’s advice while addressing his choice to include a Trump supporter among the four central characters in the story. “Da 5 Bloods” follows the former airborne GIs as they return to Vietnam on a joint mission to honor a fallen comrade – and in the process help themselves to a stash of buried gold bullion they left behind in the jungle nearly 50 years before.

Filming the story in authentic locations in Thailand and Vietnam involved hot, exhausting work but Sigel added he could scarcely pass up the chance to work with Lee. Both reflected on the seemingly natural gravitas Boseman brought to his role as the platoon leader who didn’t make it back.

“You can’t fake the funk,” Lee said in deference to the quiet sense of command Boseman showed in his performance. No one on set knew while filming that the “Black Panther” star was battling colon cancer, which would claim his life in August of this year, they said, though he did appear thin, said Lee.

Boseman’s Stormin’ Norman character plays off Eddie (Norm Lewis), Melvin (Isiah Whitlock Jr.), Otis (Clarke Peters of “The Wire”) and Paul (Delroy Lindo) as they reunite at a Ho Chi Minh City hotel in the film’s opening scenes.

The brothers in arms’ uneasy return to modern Vietnam builds cognitive dissonance quickly as surprisingly friendly locals greet the aging adventurers. At first jubilant, dancing through a tourist-trap “Apocalypse Now”-theme nightclub, they journey up the river with growing tension. “You killed my mother and father,” screams an angry produce seller after his chickens are rebuffed by the hungover Americans, triggering a bout of PTSD.

Meanwhile Peters’ character finds himself reckoning with the discovery he has left a daughter behind in Vietnam, setting up yet another moral quagmire the film deals with – the cost of America’s wars on those who must go on living in the worlds they have shattered.

As Sigel filmed, he said, it became clear that framing the guys together as they handled their challenges, often in wide shot, would be key. “It took me a few days and I realized it’s not about the closeup,” he recalled. “It’s about the group.”

Capturing an authentic sense of the period was another central challenges Sigel faced, he said, describing how he and Lee arrived at the idea of shooting 16mm film for sequences set in the 60s. Sigel, a former documentarian, saw the approach as the best way to capture the look and feel of the Vietnam era but the move initially caused pushback from Netflix, which produced “Da 5 Bloods,” he has said.

Not only did the footage require a different aspect ratio – one of four that appear in the film – but shipping the celluloid back to the U.S. for processing added logistics expenses.

The struggle was worth it, said the filmmakers. In the end, the approach – along with the bravura acting of Boseman and the others – got Lee and Sigel the gritty, murky look for the story they needed to tell, they said.