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: When Rey is unloading her speeder bike the sun is setting, but when she goes to trade her gear it's bright and sunny, and when she goes home, in the long shot on her speeder bike the sun's setting again. (00:12:45)
Continuity mistake: When Rey first meets BB-8 there are many footprints in the sand going towards it. When they walk back to the fallen AT-AT, the distance is far greater and Rey's footprints have disappeared. (00:15:10 - 00:16:30)
Continuity mistake: When Rey is fixing BB8's bent antenna, at first, the antenna is shown as thin and flexible. But as the scene changes between Rey and BB8, the thin antenna changes to a thicker and slightly more rigid antenna being held between her fingers, then back to a thinner one. (00:15:53)
Continuity mistake: When Rey is giving the scrap piece to Unkar Plutt, in the wide shot where Unkar says "What you brought me today is worth...", Unkar is holding the scrap piece upwards. The shot changes to a closer shot of the two and suddenly Unkar is holding it sideways. (00:13:20)
Continuity mistake: After Rey has fixed BB-8's antenna, she tells him the Niima Outpost is that way, pointing towards the outpost with her left arm. She holds onto the back of BB-8's antenna with her right hand and begins taking her hand off him. The shot cuts to a shot of BB-8 and Rey's right hand is suddenly off BB-8 entirely, down by her side. (00:15:55)
Continuity mistake: When the rathtars begin attacking, in a shot of Han looking down the corridor, one of the Kanjiklub members is running through a doorway whilst running from the rathtar. The camera cuts to a closer shot of them running from the rathtar, and the same Kanjiklub member can be seen running through the doorway a second time. (00:46:00)
Continuity mistake: When Maz Kanata shows Finn, Han and Chewie the lightsaber, watch the blaster strap on Finn's shoulder. When Maz is saying "Take it. Find your friend," the strap is shown on his shoulder. Finn then takes the lightsaber and the strap is suddenly closer to his neck. Then a couple of shots after, the strap is suddenly back to its original position again. (01:12:00)
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 is trying to read Rey's mind, there is a closeup of Rey saying "Get out of my head!" During this shot, there are tear streaks running down her face. In the rest of the scene, these tear streaks are gone. (01:27:40)
Answer: Any answer would be conjecture - best just watch the next movie.