For the English spoken parts (most of the movie) it lacked subtitles for most English viewers especially the elderly, disabled, hearing impaired, and ESL viewers. Disrespectful & cheap on the part of the producers especially when audio & enunciation is off.
A lot of film time spent on whistling as a form of communication. Sort of dumb, and a whole lot cheaper & more efficient to just use burner phones. Anyway, whistling as an alternative to talking (or shouting in this case) can be found through out the world. In this film it's the Canary Islands use of Silbo Gomero which remarkably can transmit fairly precise whistled word. Acting was really robotic; the crime subterfuge plot was confusing & felt dated.
Review of The Whistlers
