I think the gear was down but not locked ,IIRC from numerous rides in 130's there is a hand crank dealy for manually deploying the gear . Maybe the pilot didn't have the 3 in the green and thought the bulb was U/S
I know that there are reversionary means of manually checking the gear down with the loadmaster via intercom. That would have included a visual check for lock.
So I'm assuming that either they didn't realize the gear was inoperable or bellied in. It appears the latter with the flap settings and quick egress. Just wondering about the rear ramp deployment. Perhaps it's discouraged due to potential fire hazard?
Goin out the rear would put you into the middle of the debris field...dunno if that's the reasoning behind it, but I certainly wouldn't want to haul butt outta there, straight into a puddle of burning fuel.