Would have been nice, seeings how the challenge was bubble, if the bubble was in focus and the girl out of focus. Just an opinion though, maybe you tried it and it didn't work.
I like the sepai toning and her expression. If this was a setup shot rather than a candid, it would have been better to have her wear a plain short rather than the one with the cartoon dinosaur. also, greater depth of field is needed here, as the main focal point, the bubble, is totally out of focus.
3 - For the potential. In my opinion this shot is all about the girl, not the bubble, or even the illusion with the hand. Nice 'candid' portrait style though but... 'if only' that bubble were the dominant feature (with good focus and not cropped and probably also retaining color) for the Challenge.