The film is famous for the extreme commitment of its lead actors. Christian Bale, Steve Zahn, and Jeremy Davies all underwent to realistically portray starving prisoners.
: While the POW camp is the literal prison, Herzog depicts the lush, unforgiving jungle as the "actual prison" that ultimately breaks those who escape.
A recurring theme in Herzog's work is the of man pitted against a "sadistic" or indifferent natural world.
Here is an interesting text overview of the film’s unique production and themes: