[aruanan]

You’d think that Earth would be too small from that distance.

You can see Saturn from Earth with the naked eye. Earth, though much smaller than Saturn, is much closer to the sun and, with a high albedo, is reflecting a lot more light into space per unit area than anything farther out in the solar system. We also don't know the length of exposure, either. So, it's possible that could be Earth in the photo.

[Jonty30]

it’s understandable why you can see Saturn, because it’s so big, but to see earth the other way is surprising.

It’s like being an ant and seeing a human, but then being surprised being that ant on a human shoulder and still seeing his fellow ants.