When USCIS cashes your check...

I started thinking about this the other day and I would like to know what you guys think and/or know.

The moment USCIS cashes your check, are they, in anyway, liable to continue with your legal application, no matter what?

This question popped up in my mind because I once bought something online from Dell. It was a 27" monitor for just $80.00! Anways, long story short, it turned out to be an error on their part which caused they displayeda wrong price BUT since the transaction has been completed on my credit card account, they were forced to honor the price.. even though it was a mistake on their Web site. So, going back to the topic at hand, could something like that apply to USCIS?

I paid with money order

How to check if money order has been cashed?

I would think not.
The monitor you got was honored not because they had to, but they could.