How James Cameron Improved the Ending of X-Men: Days of Future Past
The concept for Days of Future Past arrived over Sushi at an L.A. Restaurant. Simon Kinberg had asked Singer how they could bring the cast of both the original trilogy and of First Class into the same film, to which Singer responded with time travel.
The film was a huge success, adapted from the comic book event series of the same name. The ending of the film (spoilers from here) had Wolverine wake up in a future that he himself created, having thwarted the sentinels that would have one day wiped out most of the mutant race, and his family was back from the dead.
Concerned about the mechanics of the time travel, Singer sent a near-complete cut of the movie to James Cameron, who made his time travel-chops well known with The Terminator, "I sent a cut of the movie... to James Cameron, almost finished, rough, but almost done, because I value his advice, and I pitched my time travel concept to him when I was at a party at peter Jackson's," Singer said.
After a conversation that explored "collapsing the super position" and "how it would work in quantum physics," Singer had a complete cut of the film ready. Cameron had only one suggestion on the ending.
The editor was "obsessed with this visual blurriness, so when Wolverine is walking around, he's seeing things in a blurriness, so I sent that to Jim..."
"...and so he called up and Jim goes, 'Bryan, that blurry thing made me think that the wool was going to be pulled out from under me and I was not satisfied. I thought it was going to be, it was a lie, and it failed..."
And so instead, what we get is clarity, a happier ending than what would have been. Cameron was adamant that the movie would be great, but this one change proves that every single little thing counts in filmmaking.
Source: Cinemablend