The sequence in which Dragon is chasing Mrs. Brisby through the field, up the tree and eventually into the mill's lake, watch his eyes. The original placement is (from viewer's perspective) blue on the right and gold on the left. When he chases her up the tree the gold one is visible on the right, it then switches back when the camera cuts back to a wide shot. This happens again a few seconds later near the lake.
Mrs. Brisby's eldest daughter was voiced by a child Shannon Doherty, later to become famous by her role as Brenda in "Beverly Hills 90210".