After four "Mission: Impossible" films, Tom Cruise has seen his fair share of action sequences as special agent Ethan Hunt. So many of the series' famous set pieces come to mind almost instantly: infiltrating Langley in "Mission: Impossible," climbing a rock face freestyle in "M:I 2" and now the stunt outside Dubai's Khalifa Tower in "Ghost Protocol."

When MTV News' Josh Horowitz caught up with Cruise at the latest film's premiere in Dubai, he asked the actor which famous action sequences he looks back on with the most fondness. "It's hard to say, because each one has been so different, and each had different kinds of challenges," Cruise said.

But few will deny that the iconic rappel into the heart of CIA headquarters is the series' defining moment. Cruise recalled the challenges he had filming that scene. He credits director Brian De Palma for the scene's success.

"I remember when I was doing it, my head kept hitting the floor. ... I was running out of energy, and we were running out of time," Cruise said.

De Palma said if they didn't get the stunt on the next take he would be forced to pull it off with tricky editing. "To one of the stunt guys, I said, 'Give me your pound coins out of your pocket,' " Cruise said. "I put the pound coins in my shoes, the tips, so that's what allowed me to be able to balance and keep off the floor for that whole shot. That kept my face from hitting the floor."

That wasn't the end of it, though. Cruise needed to maintain that position for the rest of the take. "De Palma knew that we had the shot, and he just held it and held it. I was like, 'How long can I hold off the floor?' Brian had a fantastic laugh, and then he said, 'All right, cut.' "

One of the projects Cruise has been attached to for a while is the long-gestating [article id="1641199"]"Tropic Thunder" spin-off for his scene-stealing character Les Grossman[/article]. There have been no signs of progress toward production, so Cruise updated us on its status.

"It's not where we all want it to be," Cruise said, suggesting that Internet shorts may be the way to go. "[Les Grossman] is so much fun to do. There are all different kinds of things we're thinking about."

Check out everything we've got on "Mission: Impossible - Ghost Protocol."

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