Ofcourse there are. This is just one example (a real exaple in comparison to all the other :P )

Does all people experience the same color or not? (not considering color blind persons)

Think about it, what is it that characterize the experice of a particular color? Nothing really except the "cultural" relations we have come to accosiate them with. And one can construct different color specras and see those too would work as a experienced color sectra. So it is quite easy to see that we cannot answer this question.

It is atleast a unanswerable question with todays technology. One might be able to construct a device which can interpret the brainfunctions that we could definitely determine the answer to this question. But somehow I doubt it (however might be possible).