(2003, Harrison Ford, Josh Hartnett)

Action crime thriller in which three red Hollywood sightseeing buses provide a backdrop for a shootout. Two are open top AEC Routemasters, the third is a Bristol Lodekka FLF6G with its Eastern Coachworks body also converted to open top, new in 1966 as Hants and Dorset 1535 (FEL428D) and still bearing that registration plate:


I believe FEL428D is the Lodekka that appeared in Mystery Men.