[galago]

In this case the OOF points of light are actually vertically oriented ovals. The idea being its reminiscent of "1974" style anamorphic lenses. Its an affectation not unlike digital retro photo filters, except that its the physical lens. Its not unlike musicians who use vintage equipment because they want to reproduce something as it was done in the past. Its gets a bit dissonant if the movie is set in the present though.

[xuhu]

I just imagined sitting for a photography course test and the first question is "why do anamorphic lenses not produce round out-of-focus points of light, since the in-focus parts are not stretched". Naturally the course material didn't cover any of this.

[nullc]

The out of focus spots are an 'image' of the aperture mask. So they'll take on whatever shape the aperture has... not its physical shape, but its optical shape.

In an anamorphic lens the image is squeezed, so the effective aperture is squeezed... well, in most of them. There are anamorphic lenses with the anamorphic part behind the iris, and for those you don't get the oval shaped oof highlights.