Audio problem: After the Red Sea parts, and almost all of the Hebrews are across the dry expanse, the pillar of fire holding Pharaoh back disappears, and the chariots head into the expanse themselves to pursue the Hebrews. A very young Hebrew boy at the rear of the masses says 'Look, Grandpa! Pharaoh and his men are coming!' and points at them with his free hand. Watch his mouth: the child is merely moving his lower jaw up and down. Apparently the child actor was too young to learn any lines so the producers improvised.
Audio problem: 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.
Answer: Although the Bible never states this, it's implied that he got to Mt. Sinai via an alternate route...after all, he did spend 40 days in the desert wandering around without any direction to go to. Afterwards was a different story.
CCARNI ★