I noticed that live, and they actually looked at it on replay. It took them 6 minutes to determine that the guy did drop the ball before he crossed the line, that the ball stayed in the end zone as a live ball until a ref picked it up after a few seconds after he had prematurely signaled TD, and that the ruling in that situation is to place the ball back inside the 1-yard line where the 'fumble' occurred, since the inadvertent signal from the ref prevented both teams from realizing there was a live ball in the end zone, just laying there. Mack Brown almost blew a gasket when he found out that it wasn't a TD but it wasn't a touchback either, which he assumed it would be since they were taking so long with the replay review.
The announcers were slow as hell to realize that the guy dropped the ball before completing his pick-6, and then during the incredibly long delay they never once commented on what should happen since the ball stayed in the end zone - obviously if it had rolled outside the end zone or if Texas had jumped on it right away it would have been a touchback.
K-State got the ball on the half-yard line, and Collin Klein scored right away.