Bears vs. 49ers final score: 3 things we learned in Chicago's comeback win

It looked like an easy win for the San Francisco 49ers, making their regular season debut in Levi's Stadium. Instead, a resurgent Chicago Bears defense used four turnovers to frustrate their hosts, and walk off the field with a 28-20 win on Sunday night.

The 49ers had control early, jumping out to a 17-0 lead. Chicago's maligned defense showed up, looking a little more like the opportunistic Lovie Smith units of old. The Bears defense had four turnovers, including two critical fourth-quarter interceptions by rookie corner Kyle Fuller. His first pick led to a Bears touchdown and their first lead of the night.

Injuries took a toll on the unit too. Chris Conte and Charles Tillman spent much of the second half on the sidelines in street clothes thanks to injuries. Jeremiah Ratliff left in the fourth quarter to get checked for a concussion.

Santa Clara's brand new Levi's Stadium made its regular season debut Sunday night. Roger Goodell was scheduled to be in the house to celebrate the $1.2 billion facility. The commissioner has had a pretty bad week, dancing around some fishy handling of the Ray Rice situation that blew up last week, so he couldn't make it.

Here's what we learned from on Sunday night.

1) ALL THE PENALTIES The first half of the game took close to two hours, thanks to 17 first-half penalties. 17! By the time it was all said and done, both teams combined for 26 penalties. The 49ers had the edge with 16 of those. And, yes, most of those flags were inexplicable ticky-tack calls, the kind of stuff that made the preseason even more unbearable than usual this year. The NFL really needs to get this figured out before they give fans yet another reason to seek alternative programming.

2) Brandon Marshall wasn't healthy, and it didn't matter. On Sunday morning, it was no sure thing that Marshall would even play. He did, and after a slow start, he ended up catching three touchdown passes, including an incredible one-handed grab for Chicago's first score of the night. Brandon Marshall on one leg is still the greatest wide receiver in Bears history.

Alshon Jeffery also played, but he might as well have stayed on the bench. Every step looked like real effort for an obviously ailing Jeffery. He was reduced to a glorified decoy. The 49ers weren't fooled either.

3) The NFC West looks vulnerable. The Seattle Seahawks lost on the road to the San Diego Chargers earlier in the day. San Francisco could have given itself a leg up in what's bound to be a tight division race with a win over the visiting Bears, but nope. Squandering a 17-0 lead and walking off the field with a loss. Aldon Smith was missed; that much was obvious from a 49ers pass rush that was lacking when they needed it most. They get the Arizona Cardinals and Philadelphia Eagles over the next two weeks, so Jim Harbaugh needs to find some answers real soon.