Filming was carried out for three years with a volunteer crew, and only stopped when the camera broke down - the last shot of the movie is literally the last piece of film that passed through the camera.
The literal translation of the Thai title is "Heavenly Flower in Devil's Hand". Since Thai doesn't have plural forms for nouns, it can also be "Heavenly Flower(s) in Devil(s)' Hand(s)".
This film is part of the Criterion Collection, spine #875.
(starting at around 39 mins) The instrument being played during the singing/storytelling is called a "khaen," a type of mouth organ using free reeds (similar to the principle applied in harmonicas) to long pipes that the player sounds by covering holes with his/her fingers. The instrument originated with the Lao culture, but has also been adopted by various ethnic groups in Thailand, Cambodia and Laos.