The 49ers led 41-17 with less than two minutes left. If you caught the final score on the scroll, you had to hope it was a typo.
The Lions somehow covered the spread, and almost tied the game to send it to overtime. They scored and got a 2-point conversion inside the two-minute warning. George Kittle, one of the best tight ends in the NFL, had an onside kick go off his facemask. The Lions recovered. Then they went on a quick drive and scored again, and hit the 2-point conversion. That made the 49ers' lead just 41-33, and they weren't covering the spread anymore.
A 24-point lead at the two-minute warning was down to eight. Had either two-point conversion failed, or the onside kick hadn't been recovered, the 49ers would have covered. The 49ers fumbled again late in the game and the Lions drove into 49ers territory before stalling, saving many survivor picks.
The 49ers were 7.5-point favorites earlier in the week, and bettors kept taking them. The line went up to 9 on Sunday and then 9.5. Anyone who got the 49ers late and somehow didn't cover, despite San Francisco leading 41-17 with two minutes left, had the type of bad beat that will linger all season.