Factual error: During the plague when the fire and rocks are falling from the sky, they fall behind a statue of Rameses and are seen through its hollow eye holes. It makes for a great image, but that would mean that the statue's eyes were punched out like a mask, even though before they were just carved into the stone.
Factual error: Ramses' sphinx was established in record time. Given the time between Moses' leaving Egypt and his return, there would not have been enough time for that Sphinx to be constructed. If the movie had conveyed the 40 year span between Moses' leaving and his return, the construction of that Sphinx would have been probable.