Other mistake: When Rameses places the dead body of his son on the statue next to his throne, watch as it cuts to a shot of the side of the statue. A dummy was used in this scene, and it becomes obvious. Check out his hair, which looks like plastic, and his eyes, which look like little circles.
Other mistake: When Moses' wife Sephora is out guarding the sheep, Moses is with his son at a tent. Sephora calls him because there is a stranger behind the rocks. When she calls you can hear that the sound is indoor-sound from a set, not outdoors. This continues when Moses calls, the dogs bark and so on.