Personally I don't think so, because the "a days journey" refers to the fact that they are a day away from Caracas and doesn't refer to the pit stop, the only thing that I might add is a comma after "pit stop" to make the middle section a subordinate clause:
At a pit stop, a day's journey from Caracas, they discussed their prospects.
I can't see anything missing here, SuprunP. They were somewhere where they made a pit stop and discussed their prospects. Anderson could have mentioned where they were when they made the pit stop, but he didn't. I don't think it's necessary. Let's see what others think. What do you think is missing?