During preparation for dinner, Lord Grantham is walking around the table and stops to pick up a card at one of the place settings. He holds it in front of him with both hands but in the next shot, he is holding it only with his left hand with his right hand down by his side.
When Tom Branson and Edna are speaking in Tom's room while he's packing, the large mirror on the dresser is filthy and smeared.
During Nellie Melba's concert, Isobel Crawley remarks to the Dowager Duchess of Grantham, 'I prefer Bartok'. Bartok's music was virtually unknown in Britain in 1922 and would certainly not have been familiar to people who lived in rural Yorkshire.