Everyone was trying to depart at the same time. The ramp, and runway would have their version of a traffic jam.

Any advice on how to quickly break up that traffic jam and get out of dodge(so to speak)?

Yep, Sit and wait, or go get a soda, read a book, whatever. Let the riff raff fight over who leaves first.

You'll be more relaxed, less stressed and have a better flight home. 

You're a helicopter pilot... OGE take off straight up away from everyone (assuming there's nothing for you to blow around) and depart away from the active low level.  Not too hard

You have never been a participant as a static display at any airshow of any import. If you did, you might not say "not too hard."

1. Wait.

2. Shortly before the end of the show you got a "call" and have to go.

3. Call tower for a present position departure.

4. In the grand scheme of things, leaving an airshow 10-30 mins later than you wanted to doesn't really seem like that big of a deal.

have dispatch put you on a fake call sufficient time before it all breaks up.

Could it be, just could it possibly be, this is NOT an EMS aircraft?