The following contains SPOILERS for Rogue One: A Star Wars Story as well as specific information about the film's original ending. If you don't want to know, then stop reading here.
We know that a great deal about Rogue One: A Star Wars Story was changed from script to screen. Between rewrites and reshoots, a lot changed, however, we know very little about exactly what was going to happen in the original version of the story. Finally, we now have some detail about how Rogue One was originally going to end. In the first draft of the script, the Death Star gets ready to blow Scarif to hell, just as it did in the final cut of the movie. However, rather than simply transmitting the plans off the surface, Screenwriter Gary Whitta says that Jyn Erso and Cassian are saved at the last minute.
A rebel ship came down and got them off the surface. The transfer of the plans happened later. They jumped away and later [Leia's] ship came in from Alderaan to help them. The ship-to-ship data transfer happened off Scarif.
The Empire continued to pursue the vessel that the plans were on while the Rebels frantically tried to copy the data onto Princess Leia's ship. According to Entertainment Weekly, They would be successful in getting the data to the princess, but just as they were, Vader's attack would breach the shield's of Jyn Erso's ship and destroy it. Vader's Star Destroyer would then turn its attention to Leia's craft, setting up the opening moments of the original Star Wars, but the film would focus on the debris of the destroyed vessel, where the audience would learn that Jyn and Cassian had made it into an escape pod, which survived because it looked like just another piece of debris.
What about the rest of the Rogue One team? Apparently, droid K-2SO's fate was sealed from the beginning, as he always died. Boodi Rook, Chirrut Imwe, and Baze Malbus were never killed because in the original script they didn't even exist. Apparently, the Rogue One team wasn't nearly as large the first time around.
The writers of Rogue One: A Star Wars Story have previously said that the first script had the lead characters surviving because they simply weren't sure they'd be allowed to kill everybody off. They were pleasantly surprised when Lucasfilm agreed with them that the crew needed to die.
This ending feels very contrived and convenient, which the writers apparently felt as well, which is why they worked to change it. Eventually, we got the ending that we all saw in Rogue One: A Star Wars Story in which everybody dies as the planet Scarif is destroyed by the Death Star. While the ending may be a sad one to a great extent, we're happier with it than we'd likely be with the original one. What do you think of the original ending? Let us know in the comments.