Paramount has enough confidence in Tom Cruise’s Mission: Impossible 5 that it moved its release date way up from Christmas to July 31. But the production recently shut down for a week or so in London because the film’s ending was deemed unsatisfactory.

Director Christopher McQuarrie was given the extra time to work out a new and improved finale with a writer friend whose identity remains a mystery and who will neither be paid nor credited.

It's unusual and costly for a big-budget film to halt in the middle of production, especially one with a release date about five months away. While one source claims McQuarrie was "scrambling" to come up with an ending that would work, a Paramount insider puts a more positive spin on the break.

"Chris, Tom [Cruise] and a third person wanted to take a minute to get from what they thought was a good place to a more perfect place," says this person, noting that if the studio had been really concerned, it would not have moved up the release date.

The last film in the Cruise-fronted series, Mission: Impossible — Ghost Protocol, released in Dec. 2011, earned nearly $650 million globally — a franchise best.