Oregon sent in their backup quarterback, Bryan Bennett, to run this play. It looks as though his initial intention was to run a Read Option and get into the end zone on a quarterback keeper.
It looks like there was a bit of a miscommunication and because he never crossed the line of scrimmage the pass was completely legal. Even though, it looks like the toss may have still gone backwards, it’s still a legal play regardless. A very impressive display of improvisation.