When it comes to names of rivers, bays, etc, you can say "Culebra River" if that were the case.
BUT regarding the film, I'm wondering if it's a documentary, a story based on a true story, the director's point of view or what?
I found these guys Blue Skies Panama offering charter flights to David and Bocas del Toro. The last time I used them, I flew between Changuinola and David flying over all the protests and road blocks saving us a lot of time.