Chitty Chitty Bang Bang (1968) -- In the movie and subsequent play, which were based Ian Fleming's novel of the same name, there is a number called "Me Ol' Bamboo", the choregraphy of which was based on morris dancing.
Global Heresy (2002) (a.k.a. Rock My World) -- Flashes of dancing by the Toronto Morris Men.
The Great St Trinian's Train Robbery (1966) -- Westminster Morris Men appear on-stage during Parent's Day. Frankie Howerd after an altercation with the side's fool wears a WMMM style tabard for the entire end of the movie.