In this question Why does Tom Hanks' character never open up the last package? the premise is clearly wrong. He does open every package except one. How to deal with such a question? Editing it doesn't seem to help because the question doesn't make sense otherwise. Now as it stands a reader can be misled if he doesn't read the comments or the (high voted) answer carefully (where it says "package" instead of "packages"). Should there be a close reason "based on a wrong presumption/misunderstanding" (similar to "simple typo" on SO)?
Usually in that case I would vote to close the question, for being off-topic, and add my own reason - that it is based on a false premise. An example where I believe that is appropriate is this recent question.
I would point out however that I think the question you've cited should remain open, but just be edited. Even though there is a false assumption, it could be easily edited to turn it into a question of why he left one package unopened, and thus a great answer like the one @System Down provided can be posted. This tackles three objectives - answering a good question, educating the OP on their original mistake and finally showing the OP that although they made an initial mistake, there was a very good question coming out of their observations.