I've got no great eye for seeing what happened, or could have happened. All I was thinking is that when you throw a timing pattern with a short field you've pretty much committed to that one pass. You've got to throw to that one receiver or the timing is messed up. Three other guys could be completely uncovered but there is no time to scan the field.
I have no idea what Goff may have seen at the line or if he is allowed to change the play once seeing how the defense is set. In his defense, Goff threw a near perfect ball and as others have pointed out there seems to have been a miscommunication of some sort with the other receivers route.
My thought is if they were committed to a pass I would have liked them to go with a longer developing play with Goff rolling out and either having the option to run it himself or pass it to another player depending upon how the defense commits.