Smith-Njigba was involved early, with the first play of the matchup being an 18-yard pass to the receiver.
Throughout the rest of the game, he made receptions of 21, 22, 16, 2, 11, and 40 yards.
At the start of the fourth quarter, Smith-Njigba caught a pass from Darnold, but ended up having the ball knocked away by a defender.
"Just a lack of concentration," Smith-Njigba said on the fumble. "Thinking about the next move, so I'll make sure that won't happen again. The ball is very important, the most important thing, so I've got to take care of that. I'll be better."
In an attempt at a comeback win, Smith-Njigba did have a 40-yard reception, his longest of the day, before the drive ended with a Darnold fumble.
"Tough one, tough battle with a good team like the 49ers," Smith-Njigba said. "We've got a lot of stuff to clean up, myself included, so just go the drawing board and get ready for Pittsburgh next week."
While Smith-Njigba knows there's some things to work on before next Sunday, his teammates have confidence that today's fumble is not indicative of his ability.