It’s “kind of a nothing, a throw-away moment” in the middle of the new big-screen comedy “Last Vegas.” But for just a single short scene, director Jon Turteltaub stuffed five Oscar winners into a minivan, bickering, joshing around and glorying in each other’s presence.

“A LOT of giggling, that day,” Turteltaub says.

“That was my favorite day,” gushes Mary Steenburgen, 60, who won her Oscar for “Melvin and Howard.” “We just sat in there telling our best movie stories, talking about people we knew in common, first getting to New York, our first jobs. If you’re going to be thrown into a cab crammed with that many people, I can’t imagine four more delightful companions to share the experience with. Those men!”

“Those men” are Morgan Freeman (“Million Dollar Baby”), Kevin Kline (“A Fish Called Wanda”), Robert DeNiro (“The Godfather,” “Raging Bull”) and Michael Douglas (“Wall Street”). And yeah, they were having a good time.

“I think what you see on the screen is the security of actors who know who they are, who have been doing this a long time and enjoy and are not threatened by other good actors,” says Douglas, 69. “They put their arms around them, embrace them and thank their lucky stars that they’re finally working with them.”

Call it the cinematic equivalent of “The Dream Team” – five Oscar winners, comedy veterans and actors flirting the with the phrase “legendary,” all gathered for a comedy about old age, old friends, old grievances and last-chance romance in Las Vegas.

But “Last Vegas” was a project fraught with peril. There’s not a shrinking violet in that cast. De Niro, 70, has a scary screen persona, and Freeman, 76, isn’t known for suffering fools gladly. Kline, who turned 66 last month, is quite shy off camera, and Douglas has been and continues to be a producer, a guy who knows how to throw his weight around to get what he wants.

“People think the ‘Dream Team’ head coach’s job is to go win the gold medal,” Turteltaub (“National Treasure”) says with a chuckle. “But the head coach is thinking his job is to not get fired.”

Douglas laughs at that, and suggests that the best posturing and posing on the set might have come from the director’s chair. “Jon’s got this self-effacing thing, where he always makes you feel like you want to HELP him. He fools everybody into trying harder. So we did.”

For Douglas, that included recognizing when “you’ve got actors having a love-fest,” which prompted him to sidle up to a producer and say, “‘My advice is to stay out of the way. Don’t try and control things. Just let it happen.’”

“Last Vegas” is about four childhood pals, now retirees, who gather in Las Vegas for the bachelor party and wedding of the Malibu member of their “Rat Pack” (Douglas). He’s about to marry, for the first time and to a much younger woman. They meet a former lawyer trying her hand at lounge singing (Steenburgen). Gambling, partying and sexual hijinks ensue – a few “HangOver-the-Hill” gags. And characters mend fences, take stock and come to conclusions about their lives.

It is “likable, amiable, fast on its feet,” says Hollywood-Elsewhere’s Jeffrey Wells. “It’s always pleasant when a film doesn’t do the expected thing.”

One thing film fans won’t see as unexpected is that Steenburgen, a beaming presence in Hollywood comedies since Jack Nicholson’s “Goin’ South,” (1978) pretty much steals the picture.

“We had this debate with the studio over who to get,” Douglas recalls, with CBS Films holding out for “a few names that were maybe better known. But Jon and I were concerned that the names had kind of a toughness about them, a slight bitterness, a sardonic sort of humor to them. But Mary? She doesn’t have that. She’s just a sweetheart, vulnerable. So a lounge singer, at this stage in her life, who’s still optimistic? That’s Mary.”

And how. Steenburgen has been plugging away at a second career in recent years – as a songwriter, working with a Nashville team that has placed tunes in a few movies and on a Tim McGraw album. But she’d be the first to tell you she has “a songwriter’s voice,” and that tackling lounge singer standards of the Great American Songbook “scared me to death. But you’ve got to do that, discover new things, even when you’re older. It’s what keeps you young.”

Turteltaub had to figure out that Freeman is brilliant on the first take, that De Niro “likes to do a line 10 different ways, all with the camera rolling” to get it right, that Kline “is the real wild card, the guy who surprises you” and that Douglas would be his go-to guy, the one who attracted the other talent and who kept the studio off their backs.

Steenburgen, who has appeared in her share of “all-star casts” (“Parenthood,” “Philadelphia”), marvels that “there were no ‘princes’ in this cast. Part of the beauty of this moment in our lives is you’re not doing it to get your next job. You’re not competitive with each other. You’re not trying to outshine each other. You take delight in being a part of a team.”

Even when you’re crammed into a mini-van with four other Oscar winners in a Las Vegas hotel parking lot.

“The thing that makes that even crazier was that we did that shot in a parking lot outside a funeral home in Atlanta!” Turteltaub says. “A little movie magic there, in more ways than one.”