Continuity mistake: After Mor'du gets crushed by a large piece of stone, and as the sun is rising, Merida removed the tapestry from Angus to place over her mother, who is still a bear, in hope to break the spell. Angus also appears to be in the circle of stones, yet, in the shot that views everyone in the circle of stones from above, Angus is nowhere in sight. (01:33:00)
Continuity mistake: When Merida is climbing the rock to drink from the waterfall the rock is several meters away from the waterfall, but a few shots later it is centimeters away.
Continuity mistake: After Elinor saves Merida's bow from the fire, it is colored white while being slightly singed. However, when Merida uses the same bow later on, the bow is now dark brown, and the discs on it are gone.
Continuity mistake: The position of Merida and her brothers' thrones switch sides before and after their meal.
Answer: They're intuitive. A regular bear would not order them about. This bear's behavior reminded them of their mother, so they made the logical assumption that it must be her.
Phixius ★