The opening scene states it is 1940 with a large number of bombers flying over Windsor Castle. They are, unmistakably, Lancasters but in actual fact the Lancaster was not introduced until 1942.
Noticed missing from the respect afforded the Queen is the fact that upon standing to leave her presence, is the moving in reverse so that one does not show their back to Her Majesty. This is not seen on any of the first seven episodes.
Mention is made of Eisenhower's preoccupation with the military-industrial complex. That term did not enter common parlance until years later, after his farewell address in 1961.
The Queen tells Lord Salisbury, when confronting him, that she believes the old saying 'never trust a Cecil' applied aptly to Salisbury. That phrase, 'never trust a Cecil' wasn't said until 1998 about then Lord Cranborne, a member of the Cecil family.