RETCON stands for Retroactive Continuity.
Which usually a purposeful change in an early part of a storyline. In this case, it's intended to fill in some holes.
So how the hell did those numerous JuJi clones that Chiba supposedly beat up get there? ([link]
What happened her was that a group of clones decided to party and get wasted back at base camp. They took a truck and went for a drunken joyride until they ran into the HKs and into the giant hole. They encountered Chiba an then woke up right before O.D. assaulted her with his chainsaw blade.PS. [link]