Mullens was 22 of 40 for 275 yards passing. Ito Smith finished with 135 yards rushing on 10 carries and a touchdown for Southern Mississippi (1-1).
A blocked punt set up Mullens' 2-yard touchdown run in the first quarter. Mullens had touchdown passes of 3 and 9 yards, and Smith ran for a 75-yard score to give the Golden Eagles a 28-6 halftime lead.
Mullens connected with Smith on a 49-yard scoring strike, and Kalan Reed had a 76-yard interception return for a touchdown in the third quarter.
It was the first meeting between the schools.