Three punts, an awful interception by Jaycee Horn, and a field goal were the results of the Falcons' five first-half drives.
Even the field goal was a letdown since the Falcons stalled out in the red zone as time expired.
At halftime, things looked up when Mariotta threw a short touchdown pass to Drake London.
His awful passing continued, with numerous interceptions dropped and one particularly egregious play.
When he went down, he tossed the ball up for grabs, and the Panthers picked it up and ran it back for a score.
If Mariota doesn't improve significantly for Atlanta's next game against the Chicago Bears.