Continuity mistake: When Han is holding Leia to his chest a close-up of her face shows his hand holding her head with his fingers near her ear. The shot changes to behind her and his same hand has instantly moved to the base of her neck. (01:34:50)
Continuity mistake: After Leia tells Han that she always hated watching him leave and he still drives her crazy, they hug and it cuts to the Starkiller Base. When we see Stormtroopers walking through the corridor and then Rey sneaking away, it's a flipped shot - note the Stormtroopers' backs, and Rey's hip bag and leather wrist cuff. (01:35:15)
Continuity mistake: When Finn, Rey, Han and Chewie are headed towards the oscillator, they stop running, seeing the battle between the Resistance and the First Order and Han says "They're in trouble. We can't leave." At this moment, the camera is behind the group and Han is standing next to Finn on Finn's right. The shot then cuts with the camera in front of them, and Han is suddenly standing in front of Finn. The camera cuts again and Han is now standing on Finn's left. (01:42:35)
Continuity mistake: When Kylo Ren and Han Solo meet on the bridge in Solo's final scene, they both stop directly next to a red bridge light. As the shots change throughout the scene, Ren is shown standing even with the red light, behind the red light, and in front of the red light. Solo's position in relation to the red light near him changes several times as well. (01:46:50)
Continuity mistake: At the Resistance base, after it's said that, "The weapon will fire in two minutes," it cuts to Rey and Finn running in the woods on the surface of Starkiller Base, and the leather cuff is now on Rey's right wrist, presumably due to it being a flipped shot. (01:50:35)
Continuity mistake: After Kylo Ren uses the Force to lift Rey and slam her into a tree Finn kneels beside her. When Ren calls Finn a traitor, Finn turns to his right and starts to stand up, but in the next shot Finn has stood up by turning to his left. (01:51:40)
Continuity mistake: During Rey's lightsaber duel with Kylo Ren, a few shots after Rey does the flip and slices the tree branch, there's a long shot of them in the forest as they're both moving past very distinctive fallen trees around them, and after a few closeups as Kylo keeps advancing on Rey, at the start of the next long shot (right before the chasm first appears behind Rey) they're back to being where they were in the previous long shot. (01:55:50)
Continuity mistake: After Rey's lightsaber battle with Kylo Ren, when the Falcon appears in the wideshot Rey's head is turned to look at the Falcon behind her, to her left, with Finn to her right, but in Rey's two closeups - before and after that wideshot, she's looking straight ahead at the Falcon, with Finn lying directly in front of her. (01:58:50)
Continuity mistake: After Rey touches Luke's lightsaber she begins to have the vision, and when she falls to the floor the blaster is missing from the back of her belt, but after she "sees" Luke and R2 and then stands up the blaster is back again, tucked into her belt (even though Rey's having her vision of things all around her, she herself is not a vision).
Continuity mistake: In the scene on the bridge when Kylo Ren kills Han Solo, if you look carefully at Kylo's lightsaber during the series of shots immediately before he ignites it, you'll see that the saber is pointed completely the wrong direction - if Kylo ignited the saber the way it's pointed in those shots, the blade would come out perpendicular to the direction it would need to come out to kill Han. Then Kylo ignites the lightsaber, and suddenly it's pointed the right way, even though he never rotated it. And yes, Kylo's lightsaber is a crossguard, but it's the main blade that kills Han, so this is definitely a mistake.
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