When something that was originally slapdash and spontaneous becomes big business, part of the fun always seems to go out of it, a phenomenon you can feel throughout “Nitro Circus: The Movie 3D.”

Hurtling skyward off a rickety ramp to do a crazy flip on a tricycle, once the kind of nutty daredevilry that gave the Nitro Circus stunt troupe its signature attitude, feels like work here more than it does play.

Maybe that’s because extreme sports have gone mainstream since Nitro Circus first gained television exposure on MTV and other outlets. Or maybe it’s because the film is structured around the creation of a live Nitro Circus stage show at the MGM Grand. Nothing says “forfeiting our rebel status” like a Las Vegas casino show.

Not that some of the stunts in this film aren’t impressive. Leaping off a 63-story skyscraper in Panama certainly borders on insane.

But only a couple of times do the stunts have that extra ingredient — wit — that makes this kind of thing amusing to watch. One such bit deserves a commendation of some kind: Nitro Circus has finally found a way to make golf, one of the world’s more plodding spectator sports, interesting.

In the troupe’s version you ride a bicycle down a ramp, go airborne and try to drop off the bike and land in a hole in a giant inflated golf ball. No bogies or birdies here; your options are either to get a hole in one or to bounce off the ball and land in a limb-threatening heap.

In the injury department, the film ends up being somewhat disingenuous. It repeatedly brags about the danger of the activities, but when one member, Jim DeChamp, appears to be seriously hurt in a car-rolling stunt, it provides few details of those injuries. Too much reality can spoil the illusion of consequence-free recklessness.