I've found a few transcription errors on BMD certs, like the wrong middle name being written, the wrong year of a marriage (the index confirms its wrong) and it makes you wonder what is wrong that you don't realise is wrong...
Family rumour can be complete baloney- one story said my great great grandfather came from Merthyr Tydfil and I've never worked out why- he came from near Carmarthen. Another said another 2xgt came from Ireland, I proved he was born in Northumberland.
As for records of any type, I tend to also go by the motto that if something seems slightly iffy, that's because it usually is. If you've got a niggle that something stinks, keep poking.