On a sweltering Sunday afternoon in Brooklyn, gaggles of film fans, black historians and political activists — not to mention Fort Greene locals — convened at the Brooklyn Academy of Music’s Harvey Theater for closing night of the BAMCinemafest and a 25th anniversary screening of Spike Lee’s “Do The Right Thing,” presented by the Academy of Motion Picture Arts and Sciences and BAMcinematek.

Beforehand, BAM hosted a reception for the seemingly endless roll call of cast and crew in attendance, a convivial reunion for the stock company who collaborated on Lee’s treatise on racial tensions in Koch-era Bed-Stuy.

Of the ten-week location shoot, Lee’s sister Joie put it like this: “We were babies back then. We had no idea what we were in the middle of. I didn’t have the scope, the insight or the foresight… I had no idea. I knew it was explosive, but it’s not as if it wasn’t what was happening around us. It was our lives.”

“It was my first real movie. I just wanted to keep my lines straight, but everyone was improvising around me,” recounted Rick Aiello, who plays an NYPD officer whose brutality sets off the film’s searing final act. “Spike gave us parameters, but it was still tough to keep up. Everyone’s going off book, I’m saying, ‘Holy sh–.’”

“And then afterwards, people would stop me on the street, angry: ‘You killed Radio Raheem!’ I actually had to change my phone number.”

For cineastes, few images could be more surreal than seeing Aiello hug it out with the actor who played the boombox-wielding Raheem — Bill Nunn, another regular collaborator from Lee’s heady early 90s output — but the two men clearly hadn’t seen each other in some time. (Between TV interviews, Lee himself bellowed “BILL NUNN!” at top volume to the delight of the film’s entourage.)

“Raheem didn’t say that much, which I liked,” Nunn explained. “I wasn’t riffing too much.” Of the now-iconic LOVE and HATE sequence, Nunn said: “It was a one-take deal. It was getting dark, and we had to get it done. We just knocked it out.”

A common misconception surrounding “Do The Right Thing” is that Lee’s 3rd feature was an independent film, when it was actually a Universal feature. But the director was sanguine about opportunities for filmmakers dealing with hot-button material today: “You don’t have to do a studio right now. Independent cinema is thriving. I think it’s a better time — the only reason why my generation went to film school was we couldn’t get our hands on the equipment.”

Of making films about hot-button topics, production designer Wynn Thomas said: “You always hope that they will help resolve the issue, or at least bring attention to the issue. The tragedy, of course, is that here we are 25 years later, and these same social and political issues are still in the headlines. Still need to be addressed.”

“If we told lies,” Lee commented, “or if I wrote a script that was a bunch of bullsh–, then we wouldn’t be here today. That’s the truth.” One thought he would repeat hours later to the BAM audience was, “We had the crystal ball. I wrote this script in 1988, March 1st to March 14th. We had the forecast on gentrification, we had the forecast on Rodney King and the L.A. riots.”

Rounding out a solid month of talking “Do The Right Thing” including an Academy panel at LACMA last week with a video message from President Obama and First Lady Michelle Obama, Lee said of the anniversary screening: “This is it.” Grinning, he added: “Well… ’til the 30th anniversary, maybe.”

(Pictured: Rosie Perez and Spike Lee at the Academy’s 25th anniversary screening of “Do the Right Thing” at the BAMcinemafest)