Gragas barrel disappeared?

In this clip we see that the gragas' barrel goes over the wall to the bush that Arc is in, but it dissapears.

With these photos, we can see that gragas throws his barrel towards the bush that Arc is in and that it dissapears without having any visual FX... http://prntscr.com/beqqk4 http://prntscr.com/beqqqd http://prntscr.com/beqqtm http://prntscr.com/beqqvi

I decided to recreate this situation with Gragas by throwing a barrel from a similar location towards the bush and got these results from the final location of the barrel. http://prntscr.com/beqt2t http://prntscr.com/beqtcm http://prntscr.com/beqtkc

You can see the barrel/cask getting ready to explode in the last photo because of the spewing liquid but there is no sign of it in the video supplied above. And even when the barrel was barely visible you could still see the green outline of the AoE radius in the second photo.

Did Gragas' barrel go invisible or was it just a visual bug that he even threw it in the first place?