Revealing mistake: When the boys are racing away on their bicycles from the Feds, the stunt doubles for Elliott and his friends are obviously way too tall to be children.
Revealing mistake: Throughout the film and specifically near the end after Jim has reclaimed Bess and the colt, there are visible horseshoes on the supposedly "wild" horses. While there would logically be a number of abandoned and escaped horses among the herd at any one time, those who joined them in a shod condition would not remain so very long in rugged country. Those born into the wild would never have worn shoes. Reason dictates there would be very few if any horses remaining shod at any one time.
Revealing mistake: As Annie gets ready to call Sandy to go to the Warbucks house, you can see the right side of Sandy's head, as they wait for the cue to send him in.