If you haven't seen Rogue One: A Star Wars Story, then you better turn away now because this is about to get real spoilery, real fast.
At the end of Gareth Edwards's film, Jyn Erso and her rebel stalwarts are successful in their mission to deliver the Death Star plans to the Rebel Alliance — but at a terrible cost. Jyn, Cassian, K-2SO, Bodhi, Chirrut, Baze, and the other rebels who went rogue never make it off Scarif alive. It's a grim ending for a Star Wars film, but it's also the kind of ending that makes sense given the stakes. However, early versions of the script had a far less tragic third act for our heroes.
In an interview with Entertainment Weekly, Rogue One's first writer, Gary Whitta, admitted that the original instinct was that all the characters should die. But that possibility was never fully explored because the creative team assumed Disney would think it was too dark for a Star Wars movie. So he crafted a more traditional ending in which a few key characters survived the battle on Scarif.
In Whitta's original ending, Sgt. Jyn Erso, an enlisted Rebel soldier instead of the street criminal she became in the final script, and a Cassian Andor–type character stole the plans and ran across the beach to an awaiting Rebel ship. Once in space, Jyn and Cassian were able to transfer the plans to Princess Leia's Tantive IV seconds before their ship was destroyed by the Darth Vader's Star Destroyer.
However, as Darth Vader goes in pursuit of the Tentive IV, the camera would have focused on a small escape pod ejected from the destroyed wreckage, indicating Jyn and Cassian had survived. (Sadly, scene-stealing droid K-2SO was always going to die on Scarif.)
It's important to note that this ending was never shot, although we know from early preview footage that an alternate version of the third act was shot on the beach on Scarif. Scenes of Jyn, Cassian, and K-2SO running across the beach with the Death Star plans in hand were ultimately cut from the final film, most likely because of reshoots.
While Whitta's original script obviously ended on a much happier note, it just didn't feel right for the film. "The fact that we had to jump through so many hoops to keep them alive was the writing gods telling us that if they were meant to live it wouldn't be this difficult," he said.
The creative team ultimately followed their initial instincts and killed everybody, a narrative choice that Disney and Lucasfilm actually really liked. So there you have it kids: When in doubt, follow your gut.