Some months ago a Falcon 900 coming up from the Sao Paulo area for a crossing into Europe had one of its throttle levers jammed.
The Capt decided to make a stop, if I remember correctly, in Fortaleza, and have the issue checked before proceeding with the crossing of the Atlantic.
Some hundreds of kilos of extra "payload" were found in various compartments in the aircraft acessible via panels that can be opened for maintenance action, inside and outside of the aircraft.
Some time later the aircraft eventually made it back to its base in Europe. Some weeks later on a routine maintenance check some "payload" was still found onboard the aircraft.