I thought of Meg Ryan for Carter too, but I wasn't sure. I think of her more as a "cute and sweet" kind of character than a more competent professional like Carter. Or at least that's what I think she was known for back at the time.
And good catch with Djimon Hounsou. He was indeed in the movie, as a character called Horus (although as retconned by SG-1 he would've simply been one of Ra's Horus Guards).