Factual error: In the scene where Robert Duvall, Michael Caine and Haley Joel Osment are in a general store/coffee shop and the young punks come in, there is a Coca-Cola machine shown that has the "Wave" logo and a slogan that was used in the 1970s, not in the time period in which the movie took place (1950s/60s). (00:47:20)
Other mistake: The uncles fire shotguns a lot in the movie, but the guns have no recoil. Shotguns kick very hard which would be easily seen.
Continuity mistake: When the lion cage is standing in the yard, sunlight and shade keeps changing. First the cage is fully in the shade, but when the uncles approach the sun is shining on it. When the cage is open, the light on Garth and on the lion's fur comes from opposite directions. After the cage is closed it's back in the shade again. (00:36:05)
Continuity mistake: When Walter's mother last drives off, all the dogs jump at Walter's window, then sit right next to the car. When the car pulls away however, the dogs are a few feet back and not in a line, but when the camera cuts back to the dogs, they are where they were to begin with. (01:26:25)
Continuity mistake: In the scene where the boys tear off the side of the lion's crate, what you see them tear off is much smaller than in the next shot. (00:51:30)