For those unfamiliar, working titles are basically placeholder names for films while the director and screenwriter come up with the one that'll be used for marketing materials and the like.
For example, The Dark Knight's working title was Rory's First Kiss, Jurassic World's working title was Ebb Tide and the first Avengers movie was called Group Hug. The whole reasoning behind working titles came from Return of the Jedi, all the way back in 1983.
George Lucas found that as soon as he told vendors and people in charge of locations that he was shooting a Star Wars movie, they immediately hiked the prices up on him. So, in order to keep a lid on the costs, Lucas came up with a fake title for Return of the Jedi - Blue Harvest.
Yeah, like we said, it's a weird one. Anyway, the trick worked and became something of a tactic for other major films. With the advent of the Internet, working titles became even more popular to try keep uber-fans off the scent and from leaking information.
When JJ Abrams came to The Force Awakens, he came up with the working title of Foodles, which has no relevance whatsoever to the story. So it goes with Rian Johnson's follow-up, which Carrie Fisher revealed on Twitter yesterday.
— Carrie Fisher (@carrieffisher) February 19, 2016
You just saw the dog, didn't you? The working title for Episode VIII is Space Bear, which we're guessing is just something plucked out of the sky for no apparent reason. UNLESS Episode VIII is all about space bears.
Hey, George Lucas purposefully edited in a five-minute musical scene into Return of the Jedi. Anything's possible.