I checked and all of the errors are simple "click" errors, which are easy to make. If the map is zoomed too far out when you are drawing the route, a click may accidentally catch a side road, creating a turn, and the next click then makes you turn again to get back on the correct route.
Other than zooming in a little when creating the route, the easy answer is to never click near an intersection. Click well before or well after the intersection.