LewC
We don't even know who did what to whom, so we're hardly in a position to comment on what anyone's BAC was or whether it'd be a problem 16 hours later. We don't even know if all of the protagonists were even operating on that particular flight. (There are up to what, 4 or 5 QF flights out of NRT on any given night, and slips can be anywhere from about 24 to 80 hours.)
Anyway, it's well known that consumption of sufficient gyozas protects against excessive beer consumption. Also, much as petrol enables driving, beer enables singing. As one sings, the effects of beer are depleted, much as your petrol is depleted as you drive. Therefore, with enough gyozas and karaoke you should be right as rain within about 40-45 minutes.
