according to a tumblr post there's a game breaking method to get stuck forever
don't use escape rope while you're in uh
wherever kyogre is fought
This is incorrect, though I guess the 200,000+ people who liked/reblogged the post either didn't experience it and assumed it was true or didn't have the attention span to look around for more than like 2 minutes. I'm sure they meant well, but spreading misinformation like wildfire is...ech.
I know this from experience because I was attempting to catch Groudon with Luxury Balls my first time around, and ended up blacking out. I decided to just take the penalty instead of reset (5,000 dollars and some wasted items, no big deal), stock up on more balls than I had before, shuffle some Pokemon around, and go back for another go. It's true that Groudon/Kyogre won't return to the place where they carried you to the core if you've already done it and leave by some means, and it's not possible to cross the lava/water again, but an alternate path becomes open at the beginning of the Cave of Origin that winds around back to the core. It's originally blocked by unbreakable rocks, but as soon as you ride Groudon/Kyogre to the core they disappear.