Impossible to know whether she was clipped or not, but I strongly suspect she was. Wrong lean/wrong foot or not, people's reflexes are too good for this to happen unless she was restrained and couldn't correct fast enough.
This is classic for those first using clips & straps or clipless pedals. It rarely happens more than once, once the correct sequence - disengage pedal, commit to that side, plant foot when stopped - becomes second nature. Over the years I've seen every variation of this problem the most amusing of which is the new rider coming to a full stop with both feet still clipped.
The other variation that can happen even to experienced riders is to do everything right and be OK with one foot and the other clipped. Then, if the front wheel is turned toward the down foot, something causes the bike to roll, such that you're now off balance toward the clipped foot. Too late, to correct, and you're laying on the ground, hopefully laughing at your own clumsiness.
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