I was surprised by this strong reflection since the flash was behind and side to the rabbit's eye.
Cats have a night vision aid in the form of - for the lack of a better word - bio-mirror behind their retina, which doubles the amount of light reaching the retina. The light bouncing back causes the cat's eye to glow in the dark.
Possibly, rabbits have the same night vision aid, causing their eyes to glow.
As the glow looks red, maybe the does bounce off blood vessels behind the retina, and the eyes glow because of larger pupil - my impression is the whole eye glows.