Well, the question you really need to answer is:
Did Deep Thought take into account that the Golgafrincham's B Ark would crash into the Prehistoric Earth and pollute the gene pool?
If you think of the Earth as program to be run in isolation from unanticipated influences, then 6 x 9 would imply a mistake. However, given that Deep Thought was created by Pan Dimensional Beings outside our normal Universe's space-time continuum it is reasonable to conclude that this race and the machine they constructed to determine the Ultimate Answer to the Ultimate Question could see every event in time and know that the Golgafrincham's Ark had been programmed for a collision course with a small blue-green planet they would call Fintlewoodlewix.
If a question is asked through the construction of a living computer, The Earth, within a dynamic Universe that will interact with it rather than, as in the case of Deep Thought, outside of its ordinary dimensions, you can bet that there is a good reason for this change of context. It seems very likely that the whole history of the Universe was being allowed to affect this backwater of the Milky Way.
Just think about the time-complexity of the original Answer. What do you imagine were the input parameters?
