My father flew them in Burma in WW2 doing supply drops to the ground troops. No parachutes, they just got about 1 ton of rice into a much larger bag with lots of slack, overflew the drop zone, several lads at the back booted it out of the open door. Apparently it slowly went out, then there was a golden moment when it picked up its own momentum and out it went, which the loadmaster, eyeballing the drop zone, had down to perfection. No safety harnesses down the back apparently. "Just don't fall out son." Then round for another one.
The bags didn't usually burst on impact unless they hit a tree. What if it did burst though ? Hey ho, it's rice, it's going to be boiled anyway.
I've wondered about the effects on trim as it came out, on one side, then suddenly fell away.
I heard about it plenty as a kid. I've often felt I could still fly from Rangoon to Mandalay without charts, just from memories of tales of "following the river".