If you were subject to a check, the gadgets that the staff use to check cards will simply confirm that you tapped in at the start of your journey and haven’t tapped out yet. If you are found to be “in the system” in this manner then you’ll be free to travel. There is no zone validity type indication of the sort you describe that can be stored anywhere so you’d be fine.
If you didn’t tap in then it probably deducts a penalty fare or something. (The actual detail of how it works is potentially different between Oyster and contactless travel so I’ve generalised a bit.)