Rivers made a horrible decision on 1st and goal; the safety was inside Gates and would've made that pass an incompletion at least. On that play he should've thrown it away.
IMO, Mitchell was supposed to play the slant but left his post early because the QB never took his eyes off the TE. Greer was supposed to play the fade or out? He wasn't when you look at that replay. If Jabari was 1 on 1 with his receiver, then he did have inside position on him but could've been exploited on the corner route for the TD. On the other side of the field, the WR should've run an out or corner fade and would've gotten a completion if not the 6. This was a badly drawn up play because Mitchell had both the WR and TE covered.