M. Night Shyamalan declared in an interview that the plot was inspired by the Washington D.C. "Operation Flagship" sting operation on December 15, 1985, which was organized by the U.S. Marshals Service and the Metropolitan Police to lure wanted fugitives to the Washington Convention Center under the pretense of free tickets. It resulted in 101 arrests, one of the largest and most successful mass arrests of fugitives by U.S. law enforcement.
While being distributed by a major studio (Warner Bros), Trap was allowed to resume filming under an interim agreement during the SAG-AFTRA strike as M. Night Shyamalan independently finances his own films.
For conversational scenes in which actors would look into the camera lens, M. Night Shyamalan attached a one-way mirror to the lens that would reflect off another mirror and allow the actor in close-up to see the other actor.
When M. Night Shyamalan was figuring who to cast as the lead in "Trap", Josh Hartnett went to Ireland during production of The Watchers (2024) and had lunch with him. The two talked about Oppenheimer (2023), Black Mirror (2011), and living outside of Hollywood. When they talked about being fathers of three girls each, Shyamalan knew Hartnett was perfect for the role.
Songs in the film were performed on stage as if it were a real concert. Cora Kozaris was the choreographer, and a videographer recorded onstage material and projected it onto the stadium's screens in real-time. The shoot involved thousands of extras, who were not told what the film was about but received Saleka Shyamalan's music beforehand to be able to sing along. Josh Hartnett recalled multiple extras consoling him because they thought he was nervous and were unaware of the character he was playing.