Factual error: The schoolmaster chastises Belle for teaching a little girl to read. But in 1692, a time before the story is set, King Louis XIV issued a royal decree requiring villages to establish schools and requiring all parents to send their children - boys and girls - to the village schools until they were 13 years old.
Factual error: The family's roadtrip was during "summer vacation", but there was intermittent Fall foliage (yellow, orange, red leaves) during their four days traveling. Quite often, the foliage was closer to what would be expected in late September or October and even November.
Factual error: "Colonel" Roderick has incorrect rank insignia on his collar. Looks like Sergeant First Class (three above, two below).
Factual error: The musicians in the (real) Band of the Coldstream Guards that plays Happy Birthday for Christopher Robin are wearing their 21st-century uniforms and medals.