Star Wars: Rogue One - 10 Major Plot Clues From The Final Trailer

10. It'll Start With A Flashback

The trailer opens with a young Orson Krennic flying down to the home of Galen and Jyn Erso - approximately around 15 years before the events of the movie, based on the age of Jyn here.

It's a bit simplistic to assume that opening the trailer = opening the film, but in this case it would make a fair bit of sense. The trailer makes it look as though this is Jyn having a flashback, so it'd fit to open with it, then cut to her in prison, and then begin the movie in the proper timeline.

The only other placement for the flashback would maybe be when she's brought before Mon Mothma and told about the message from her father, but that would risk interrupting the flow of the movie at that point. So it seems like what we're seeing here is how the movie begins: Krennic taking Galen, and Jyn witnessing this and then running away.