I know at my airline we have had crews take the wrong airplane in the past (before my time). Signing into the plane on our EFB has all but eliminated the chance of doing that now. Sign in fails if you try.
But back to your question. On our planes the N-Number is on placards on the panel, but it is very easy to just not notice. Leaving an outstation at 0330 (home time) we once went to the wrong plane and didn't notice until I was 75% done with the walk-around (ground crew flagged us down). CA was inside talking to the company, unable to sign into the plane because the plane had been changed overnight to a different gate but the board still showed the gate we went to.
We do also check the documents are present, correct, and not expired. Never seen one wrong, yet