If you watched World War Z and thought the ending seemed out of place, there's a good reason why. After the battle in Jerusalem, the movie ended on a jarring small-scale switch, with Gerry wandering around a research laboratory—but the ending we got was the backup option for the original script, which finished things off in far more epic fashion.
In the original ending, Gerry and his sidekick Segen made it to Russia and joined the anti-zombie army. The story then skipped ahead to the winter, showing Gerry leading the Russian army into massive zombie battles. He contacted his wife Karin, who revealed she'd turned to prostitution for survival—and that she'd left him and was in a relationship with one of the soldiers we saw at the beginning of the film. Not about to lose his family, Gerry embarked on a quest across Siberia, trying to reach the Pacific Ocean and find a way to his wife's camp in America.
It's a downer ending that would've set up a whole trilogy of World War Z films, but this wasn't just a script idea—most of the third act was actually filmed, but at the last minute, Paramount decided to go with a lighter, more hopeful ending. The reshoots ended up costing $25 million. That's a huge amount of money, especially since none of the original third act was used in the final cut. Frankly, the original version sounds awesome. We never knew we needed a bearded Brad Pitt leading the Russians into epic zombie battles, but now they've got to make a sequel featuring that storyline.