The Cardinals suffered a potential big loss in the third quarter when second-round draft pick Ryan Williams was carried off the field following his only rush of the game.
Arizona Coach Ken Whisenhunt said Williams might have suffered a ruptured patella tendon, which would knock him out for the season.
The Cardinals had a 20-14 lead heading into the fourth period but Flynn hooked up with Chastin West for a 97-yard touchdown on the first play of the quarter. Harrell threw a 6-yard scoring toss to Kerry Taylor with 5:03 remaining.
Green Bay starter Aaron Rodgers had a 20-yard touchdown throw to Greg Jennings in the first half and was 9-of-12 for 97 yards in three series.
Kevin Kolb played three series for the Cardinals and was 6-of-11 for 80 yards.
Both teams are 1-1 in exhibition action.