hmmm... well shouldn't the balloons create a shadow on the elephant?

I think the elephants shadow is too stretch for the suns lighting. The shadow you've made is more for if the sun is closer to the horizon. Try making the shadow less stretched an closer to the elephant...

If the balloons were lifting the elephant i believe the rope should be pretty much vertical instead of curving around the elephant...

And last of all i think the cutting out of the elephant is too crisp try blurring the edges a little. There's also a light glow on the right edge...

hopefully that'll help somewhat