Did the stunt wizards in “Iron Man 2” really destroy a Rolls-Royce Phantom? Or was that just movie magic?

Actually, the filmmakers trashed two identical Phantoms, each costing $438,000, according to John Armstrong, who worked on the film’s stunts and special effects. The remains sit in a prop storage facility in Downey, Calif.

“Rolls-Royce built us two identical cars,” Mr. Armstrong said in an interview Wednesday, prior to the movie’s opening on Friday. “Because their cars are hand-built, they never build any identical cars, but they did for us.”

Karen Vondermeulen of Rolls-Royce North American wrote in an e-mail message: “Yes, we did make two Phantoms for the film, though, I am not sure if we can say 100 percent we have never made two identical cars before.”

Actually there was one small difference between the two Phantoms; sharp-eyed viewers may note one car has the optional “coolbox” in the back seat; the other doesn’t.

But how did the filmmakers create the effect of the Phantom being cut to pieces? By actually cutting it to pieces.

This was done before filming began. The sheared-off panels were then wired with pyrotechnic devices, glued back together and smoothed out with Bondo and Mylar. Then, they were ripped apart with the charges while the cameras were rolling.

The filming for the sequences involving the Rolls-Royce was supposed to have been done in Monaco last year, a couple of weeks before the Grand Prix there.

The filmmakers had been given permission by the government of Monaco to film on the race circuit, but Formula One’s chief executive, Bernie Ecclestone, overruled the decision, Mr. Armstrong said. “We did end up flying one of the Rolls-Royces over there, and we filmed it driving down the course.” Racecars that were also in the scene, zooming past in the opposite direction, were “computer-generated,” he added.

Most of the sequence involving the movie’s fictional “Grand Prix de Monaco Historique” (based on a real race that was just staged May 2, by the way) was filmed in the parking lot of Downey Studios — formerly a manufacturing plant where the original Space Shuttle was built, in Southern California.

Set builders re-created several turns and two straightaways of the Monaco circuit, put up catch fencing, guardrails and grandstands. “We even put inflatable patrons in the seats,” Mr. Armstrong said. A huge “green screen” built behind all the action let film editors key in wide shots of the Monaco skyline and harbor.

Where did all the racecars come from? Eight were supplied by the Historic Grand Prix Association. Some 19 additional cars were built by Mr. Armstrong’s crew, using molds they created based on 1978 Wolf Formula One cars. Only 2 of the 19 were actually running models. They were equipped with 320-horsepower, 350-cubic-inch Chevrolet V-8 “crate motors.” “They are real racecars, capable of 100-plus m.p.h. speeds,” Mr. Armstrong said.

The blue and white Stark Industries race car was driven by the stunt driver Tanner Foust. The yellow Kodak car, the only other vehicle that was capable of running had the driver’s name of “Elon Musk” painted on the side. Mr. Musk, the chief executive of Tesla Motors, had allowed the filmmakers to use his SpaceX facility in Hawthorne, Calif., as the site of the film’s “Hammer Industries.” He also made a cameo appearance in the film.