“Mandela: Long Walk to Freedom” is an exciting movie. So’s watching those watching it:

Guy Oseary, who manages U2 and Madonna, too, has six fingers. The sixth being a cell permanently grafted to his palm . . . Zac Posen kept fluffing some fluffy parading a new silk fluffjob . . . Salman Rushdie, who hasn’t missed an opening since his first wedding night, waited to hit a TV camera on the red carpet . . . Chef Bobby Flay: “I’m here because my restaurant’s across the way.”

Idris Elba plays Mandela. Tall, handsome, gorgeous teeth. Brit accent. Friendly. But no pistol to interview. “I never met Mandela.” How’d he get this role? “It’s been a journey.” Learning his mannerisms? “I studied his documentaries, books. I didn’t want an imitation.” About playing the age range? “It’s interpretive.”

Interrupting this riveting chat? Harvey Weinstein all in black — suit, shoes, socks, shirt, suspenders, demeanor. He growled: “Cost fortunes making wide-screen films and you watch CDs at home on TV.” But Harvey always growls at me.

Iman. Gorgeous. “My clothes, all photographed, are stored in a garderobe. This fur-trimmed coat they delivered in five minutes. But my dress is only $39.99.” Maybe because it’s so short. Anyhow, the grey cashmere coat’s 20 grand. Also in grey, host Andrew Saffir who mumbled: “Grey’s the new black.”

Naomie Harris, the movie’s stunner from “Skyfall”: “This filmed in Capetown. I’d been in South Africa before making ‘Blood and Oil.’ Mandela was too ill to meet me but I had dinner with Winnie, his wife during those turbulent years. I’ve seen the movie twice. Tonight’s my third time — a maximum even for MY films.”

U2 — Bono, The Edge, Adam Clayton, Larry Mullen Jr. — wrote the story’s theme song. Individually and collectively they said:

“We’ve fought AIDS since our late teens. Did our first apartheid concert in the late ’70s. In Ireland indignation level is at a higher pitch than in other countries. It’s a big deal. One player tied himself to a coach en route to a Rugby game. And got hissed. Beaten up. Look, apartheid, the future of our divided country, lays out the argument for grace not revenge. As for our song, we tried to avoid one that dealt with the history of the country.”

You can just call him ‘Jackson’

Cheyenne Jackson in tonight’s one-man show at Birdland: “I’d prefer a plain name like my siblings John and Amber. Starbucks calls out ‘Shinay’ . . . ‘Shayann . . . Shane’ . . . so now I just say ‘Jackson.’ My part-native American father was subconsciously honoring his Cheyenne blood.

“I’m close to my folks. My biggest supporters. I moved to be near them. Starting in showbiz, I was green. I auditioned cold in front of a tableful of Tony winners. Who knew them? I had only chutzpah.”

Chutzpah paid off. His debut album “I’m Blue, Skies” just came out.

Bullet points

St. James’ “Bullets Over Broadway” redo opens March 11. Steve Schirippa who’s in it: “We’ll run until they tell us to go home.” . . . “Night at the Museum” filmed in London. Ben Stiller got stuck in the museum one night all night . . . Backstage at “After Midnight” Fantasia Barrino’s teacup Maltese wangles into her VIP photos . . . Alan Alda and party of 15 did turkey, as always, at upstate’s Mohunk Mountain House.

Odds & ends

RFK’s sons Chris and Maxwell went sailing in subzero holiday weather . . . Ben Bradlee Jr.’s new book “The Kid,” about the Ted Williams family, got celebrated on the baseball field. The Kid and the dad were not close . . . Jane Kean, last of the Jackie Gleason “Honeymooners” (played Art Carney’s wife Trixie Norton), was my friend. Once spying her last name billed in caps, she forever introduced herself as: “Jane Kean!”

Lady of a certain age: “Nothing’s working. My sockets are dry. Waterworks won’t work. What shouldn’t leak, leaks. Squeaks. Or creaks. Knees won’t bend. Hands don’t close. Elbows ache. Everything on my body needs fixing.”

Only in New York, kids, only in New York.