Page "Manos: The Hands of Fate" Paragraph 31

Warren decided to shoot night-for-night scenes, because many of the cast and crew also held day jobs.

In many of the night scenes, the camera and lights attracted swarms of moths, which can be seen in the film's final production.

In the scene in which the cops " investigate " Mike's gunfire, they could walk only a few feet forward, because there was not enough light to illuminate the scenery for a panning shot, creating the unintentionally amusing impression that the officers hear the gunfire, step out of their car, consider investigating but then give up and leave before making a proper check of the scene.