If the guys unloading the aircraft had filed the appropriate report
It surprises me that HKG even picked up the discrepancy. I'm guessing that the pallet in question was a shipside transfer to another aircraft and it was probably during the loading of the other aircraft that the discrepancy was discovered. Presumably the pallet tag was 1,000 kg more than the weight shown on the inbound Load Instruction Report (and therefore the Loadsheet) and the LIR of the receiving aircraft.