Their Directions were WRONG when they split up, on foot.
Apparently, they live in a world with this:
...........W........
............|.........
......N.--+--S....
............|.........
............E........
which is obviously wrong.
...............Charles
.................../\
.........John <<>> Peter
...................\/
................ EAST
The biggest flaw was the mistake when the three split up... someone doesn't know their directions or how a compass works.
Charles (Brolin) said he was walking West, told Peter (Waterston) to go South, and told John (Simpson) to go North.
From our view... Charles walked away from us; Peter went to the right; and John went to the left.
In the real world...
Either Charles went East instead of West OR
John went South instead of North and Peter went North instead of South.