Hrm..I thought this question was very fair.
I think you could have argued a number of things. I guess my approach to it was to first note that it said the WORLD of physical journey's (didn't it..I'm too lazy to go get the paper) - i.e. not just on the journey itself.
So my first point was the most obvious, relating unexpected detours to the obstacles which come up on a physical journey and how they are unanticipated.
Second point, which was meshed in altogether was about the way in which inner growth and understanding (an alteration of self) results from a physical journey. I don't if I made this work right, but it sounded good at the time. I argued that this was an 'unexpected detour' for the traveller, who would not have anticipated such an alteration in their self as a result of their physical journey.
That's about it! Not enough time though
Only got through 9 pages!!! ARRRRGH~! Medium sized writing..got bigger at the end, when I had like 2mins left and I started writing like 4 words per line haha