I knew this play was familiar. Check this video out.
Very similar play, built off the same concept.
@Delvin, after watching this video, I take back what I said. It looks like the throw to the slant was really built in to the RPO play. Seems like a pre-snap box count (8 in the box) led to Tua throwing to Parker on the quick slant.
It might not have been an audible per se, but still giving props to Tua for executing the play efficiently.
Thanks for the video. Agreed on the props.