At the private after-party, hosted by The Branding Bee on the city's famed Sixth Street, the pair munched on beef sliders, jalapeño poppers and quesadillas as they held court in a secluded corner of the room, mingling with reps from the film's production company.
Fergie wasn't showing in a loose-fitting black top over black tights and lace-up boots. The singer seemed relaxed and in no rush to head for her hotel bed as the clock ticked past midnight. She sipped on water as her husband, who wore a gray V-neck T-shirt under a brown blazer, sipped Diet Coke by her side.
About 100 people attended the party, which was kept lively with tunes spun by New York City's DJ Cash, who flew in for the occasion.
Earlier in the evening, Fergie, 37, accompanied Duhamel, 40, to a red-carpet opening and screening of his film about longtime friends whose pickup truck breaks down in the middle of the desert, leaving them stranded.
"When we were shooting [in California's Death Valley], I tried to spend as much time as I could in solitude," Duhamel told PEOPLE. "I would go off and just sit. Twenty minutes out there by yourself is a long time. It's very desolate and other-worldly – you almost feel like you're on another planet."