Continuity mistake: When Rey rescues BB-8 from the scavenger Teedo, the top part of Rey's outfit is crisscrossed with her right side over left, but when she shushes BB-8 it's crisscrossed with her left side over the right. Then it's back to the original way. (00:15:25)
Trivia: A model of the tumbler from The Dark Knight trilogy is spray painted on the white hull of the Millennium Falcon, and mounted to its underside. This is because there was a friendly competition between JJ Abrams and Zack Snyder to see who could one-up the other by putting Batman/Superman references in Star Wars and vice versa.
Answer: The First Order already has the piece that R2-D2 was carrying as well. That is the first piece, the large piece of the map missing a small section. The second piece is carried by BB-8 and only by BB-8, the missing piece in the map. All the first order needs is that second piece, and so does the Resistance. However the Resistance needs R2-D2 to activate again so he can show them the first piece, so they can put the second piece in it.
lionhead