As for putting a mobile still in its case into rice... no way, it will not work simply because moisture can stay inside mobiles indefinitly unless they are opened up so forget the rice idea.

The gap between surface mount components and the pcb can be so small that it has to be blown out or hung up so it evaoprates and has a way out to disperse, so how do you get grains of rice that close to "draw" out moisture?, will never work if the pcb is still inside it's case.

The biggest failure would have to be the lcd display and even that can be washed and dried out if you know what your doing.