How do you know that they're stars? I believe they probably are stars as well (by visual comparison with a star chart, suitably rotated), but I've found no source for either claim.
I did find multiple sources, including TFA, for the brightest being Venus.
Why would you think they are not stars? Not really sure the confusion on the matter. Are we leaning towards this being shot from a soundstage?
They're much brighter than the noise floor. Photographic noise doesn't really have such outliers.