Trailers are released very early now while the films have not even finished editing or begun standard reshoots. Scenes, if not the entire movie itself, can be drastically altered within weeks. Van Damme's Cyborg, Star Wars' Rogue One,vand Alien 3 are examples.
Case in point - the Avengers: Age of Ultron trailers. The scene of Quicksilver running inside the train car went through changes in each trailer. In one, it's daytime outside the passenger window. In another trailer, it is night. In another it appears to be in a tunnel.