Does it matter whether it was the real flag?
Woven throughout the film, which is based on a book by David Friend, are discussions about the powerful nature of a flag.
"We're not a country based on religion or ethnicity, or even cultural heritage" Burns told the filmmakers. "We're a country based on ideas and a philosophy. And that's what the flag is."
Jodi Goglio, who works for Eder Flag, said a flag "makes you feel that we are bigger than just ourselves."
A young crew member of the USS Roosevelt wiped away tears as she described having the supposed WTC flag on board.
"It just makes what you're doing so much more, wow, meaningful," she said.
When asked whether it mattered whether the flag was recovered, a visitor to the 9/11 memorial said, "It would matter. It would matter to me." Another said, "I think it would to the families who lost their loved ones." Among those who died were 343 firefighters.
Thomas Koehler, a retired detective with the New York Police Department, said he would rather not know what became of the WTC flag.
"If you had the actual flag ... the cynic in me (would say), people want it. You put a price on it. ... then it becomes something else."
Tucker got a firsthand taste of a flag's power while making "Gunner Palace" with Epperlein.
Released in 2004, the documentary tells the story of a group of American soldiers who fought in Baghdad.
The Iraqi insurgency was growing, and Tucker, an American, wanted to leave in spring 2004 for his home, then in Germany.
He stayed at a U.S. facility at the airport and awoke to find a small folded American flag under his pillow, a customary gift made by some group.
"I was so overwhelmed with emotion. That flag means home," Tucker said. "While that experience is not uniquely American, when you are thousands of miles from home, under stress, and you see the colors -- it reminds you of your people."