The breasts are bulging outwards, her upper body is down by her knees and the knees are touching the fairly large breasts. Then the relatively short right shank....
Someone who is slightly more flexible than I could get into this position (A fat guy almost succeeded). At first glance it did look impossible until I noticed that her hair was hiding where her back would logically need to arch.
The problems to my eyes are limb length (Left arm and right leg are both too short), breasts (She's too close to the floor and her knees should be far enough forward to push them under her arms), and, most noticeably to me, the broom (the handle would need to have strong double curve to touch her knees and pussy at that inclination and still appear straight).
Of course I like her expression well enough that the relatively minor artistic errors don't bother me.