The brain is something i've had to learn a lot more about over the last year and we are literally scratching the surface in terms of understanding how it operates.
The thing is, if you have a false memory, you have no method of distinguishing it from any other memory that you have, its just a memory that happens to be wrong. False memories can be triggered by a variety of things and you would never know that you had it because you 100% believe it happened. It's true that our brains have a certain capacity for checks and balances so that we can deduce by logic that something may not be correct, but we can never know for sure