Damon Lindelof has discussed his World War Z rewrites, Digital Spy said.

Lindelof was brought in by the producers of the Brad Pitt-starring apocalypse drama to rework significant portions of the screenplay, after principal photography had already finished.

Discussing the unusual move with Vanity Fair, Lindelof recalled Pitt's explanation to him at the time.

"We started shooting the thing before we locked down how it was going to end up, and it didn't turn out the way we wanted it to," Lindelof quoted Pitt as saying, before asking him to watch an early edit of the film.

"The thing we really need right now is someone who is not burdened by all the history that this thing is inheriting, who can see what we've got and tell us how to get to where we need to get."

Lindelof goes on to explain that the film's ending, as it stood, was a major problem, along with sections of missing footage which made certain plot elements incoherent. He re-wrote the ending, and roughly 40 minutes of additional footage were shot.

The full article goes into depth about the other setbacks on the Marc Forster-directed project, including a mis-filed stack of invoices which caused the production to vastly exceed its budget.

Pitt recently suggested that the early cut of the film was "too political" and became bogged down in a serious message.

World War Z will be released on June 21.