The first shot isn't one ant moving slow, but a collage of several ants walking hundreds of times over the same area, stitched together from ~6 hours of footage.
Almost two dozen actors died during production, many of them only seconds after biting the director.
The sound the ants make are crumpled post-its touching.
To achieve the goal of having exclusively shots of the blue sky or grass field, some of the shots involving the sky are filmed in front of a green screen.