Factual error: The main character Lewis Morgan is supposed to be a British Army Colonel, but his uniform is wrong. Full Colonels are classed as Staff Officers and wear a Red band around their Service Dress Cap, a Staff Officers Cap Badge (a lion on top of a crown) and Red collar patches. It's also unlikely that a person would have reached the rank of Colonel without any medals which would be worn on Service Dress. (01:20:00 - 01:22:00)
Factual error: The buttons on Keira's twin-set cardigan would have matched the cardigan colour. Light buttons were a cost-cutting exercise many decades later.