Today there was a scrimmage in Auckland and I’ve just got a question about a scenario we had.
In one match, our doubler barrel was balanced on the top of a 30" goal and when our alliance was loading a negator barrel, he accidentally knocked the field wall and the doubler barrel fell off (the whole goal was shaken slightly). Would the doubler barrel still count?
Thanks,
George 
Let’s take a look at the applicable rule from the VEX Gateway Game Manual. Some text has been bolded for emphasis.
Let me begin by saying that these types of situations are very difficult for referees to handle. If accidental contact with the field causes a change in score, the referees will attempt to score the match as if the contact never happened. This may not be possible in all circumstances. (For example say a doubler falls off due to human contact with the field, but is then rescored legally in a new goal?) The referees will do their best to ensure the proper scores are tallied, and in the case that accidental contact affects who wins the match, they will disqualify an offending team if necessary.
In the example you described, it would seem as thought the doubler barrel should have been counted. Of course, without seeing the specific incident, it’s hard to make a blanket judgement.
Thanks Karthik! This has really cleared it up for me.
You’re welcome!