I did reproduce the error, but instead of staying there,some combination of taking a screenshot, pausing the game, and changing speed meant that instead of hanging, the keg slowly went down the return pipe.
When I was experiencing the error, other pieces would collide with it and form a junk piece which would also hang in that spot. However, as I said the error did not reproduce and the level completed and I was able to get to the end of the game! I did include a screenshot of the hanging keg just before it began to resume movement.