The ambitious 3D film, which cost $225 million to make, has been plagued by production problems -- including reshoots, multiple release date changes and a ballooning budget.
One producer source told The Wrap last year that making of the film had been "a nightmare" for Universal. "47 Ronin" will have to make more than $500 million to break even at the box office.
One of the reshoots features Reeves' character battling a human-dragon shapeshifter, seen near the end of the trailer above.
"47 Ronin" hits theaters Christmas Day.