Use of music
This movie got me thinking about the soundscape. Frequently in the film there would be strings amping up tension or making the scene feel off-kilter (in a good way), and it was well-used mood music, but I couldn't help but wondering if the film couldn't have been better with less music, simply filling out scenes with ambient background noise.
A big part of the film is ambiguity, and I wonder if the tension might not have been raised and the twisted guesswork of "what is that person *really* up to?" might not have been heightened by removing music. If it felt like a documentary more often, maybe I would have felt more uneasy.