The NBA does have replay, though. I guess it wasn't triggered here because the ref called a Technical rather than a Flagrant. It doesn't look like they can rescind a foul call completely after review, but the refs could change it to a common foul, which would have prevented the ejection. Also, the refs would have been allowed to call a Technical on Embiid for unsportsmanlike conduct based on the review.
But hey, if the NBA doesn't work out for him for whatever reason, Embiid may have a future in soccer.