Epic collapse indeed! That was followed by epic ineptitude by the Colts. They were terrible!
Here's a pretty good piece on why the Packers lost.
1. Mike McCarthy's conservatism. Twice in the first 10 minutes of the game Green Bay found itself with fourth-and-goal within reach of the goal line, and both cases McCarthy folded and settled for field goals. Those weren't the only reasons the Packers lost, but failing to put up a bigger lead early gave the Seahawks enough hope to clamber back into the game.
On the road, hostile crowd, brutal defense on its heels ... why not go for the throat before many of the fans have found their seats? Seattle surrendered five turnovers, including an uncharacteristic four Russell Wilson interceptions; Green Bay's inability to capitalize on all of those stands as the greatest reason the conditions for this collapse even existed. But if we're going to get more specific, we can.
2. Morgan Burnett. With five minutes left in the game and Green Bay up 12, another Russell Wilson pass ended up in Green Bay's hands. Burnett caught the ball at midfield and had room to run. Whether he panicked, whether he feared fumbling, or whether he, like most of the rest of America, believed he'd just clinched the game for Green Bay, Burnett hit the ground and slid. Had he moved further into Seahawk territory, he could have set up, at the very least, another field goal that would have further tighened the screws on Seattle. Instead, the Packers soon punted, and less than two minutes later, Seattle was in the end zone for the first of its three late touchdowns. That would be immediately followed by something even worse for Green Bay, though.
3. Brandon Bostick. Heaven only knows why tight end Brandon Bostick decided to get fancy and go up for an onside kick reception instead of blocking for the far more sure-handed Jordy Nelson right behind him. That bounce off Bostick's helmet landed in Seattle hands, and barely 30 seconds later, the Seahawks had scored an improbable go-ahead touchdown. Oh, but the pain wasn't done for Green Bay yet.
4. Half the Packer secondary. After scoring the go-ahead touchdown in regulation, Seattle was up one with 85 seconds left. So of course it had to go for two. But did Green Bay's secondary have to stand around watching as Russell Wilson heaved a ball that was far more duck than hawk?
Luke Willson grabbed it and the collapse was nearly complete. But still, there was one more question...
5. Why didn't Green Bay target sore-armed Richard Sherman? The Seahawks' all-everything cornerback set the tone for this game early by intercepting an Aaron Rodgers pass in the end zone with spectacular authority. But a collision with teammate Kam Chancellor left Sherman's left arm so sore that he held it against his body as if in an invisible sling, play after play. And yet, Green Bay either never noticed Sherman's injury (or perhaps thought he was faking for effect), and thus never took advantage of a huge matchup edge.
So there you have it: a collapse for the ages, with plenty of blame to go around. This one's going to hurt for a long, long time in Wisconsi