Why does JBU1825 from Ft. Lauderdale to Lima show a large zig-zag in the route?
It isn't, as a screenshot taken later in the flight will show:



The dashed line is FlightAware's attempt to plot the planned route of flight. It's not always accurate, and FlightAware sometimes includes strange zig-zags. If you go to skyvector.com, choose "Flight Plan," and paste in the route shown by FlightAware (BEECH5 BAHMA URSUS UL780 TBG UL780 VAKUD UL780 TRU UV1 ATATU ATATU2), you'll get the more logical route that appears to match the actual flown route: