Factual error: There's more PIR's (movement detectors used in security systems) in Hireclere than you could find in a security warehouse! Just look behind the actors in the corners of a room about 8 feet up. White plastic things about the size of a packet of smokes. I think the earliest units on the market started appearing around the early 70's. The PIR's in Downton Abby look to be around the late 80's onward - pretty advanced for 1914.
Continuity mistake: In several episodes of the early seasons, Carson is said to have once been part of a music hall song-and-dance team with Charlie Grigg, who comes to Downton to blackmail Carson. But in later seasons, Carson is said to have come to Downton at a young age, serving as a hall boy.
Continuity mistake: Every letter's handwriting looks the same - no matter who wrote it.
Character mistake: At one point they say the gramophone was gift for Sybil's wedding. Later they say don't play the gramophone from Mary's wedding, it will make Edith sad.
Answer: Yes, because at the time it was not sure if it would continue and since it was short it could be seen as a miniseries. it also depends on where the producers decide to submit it. However since it continues on it is no longer a miniseries but a full series and thus cannot be submitted in the miniseries category anymore.
luke f