Continuity mistake: When Finn is going to an escape pod to run away, he puts his pack down in front of it, seen again in a later shot. When Rose realises he's trying to run away, his pack has moved itself inside the pod.
Continuity mistake: When Rey is following Luke up the hill in the infamous milk scene, her holster switches from being on her right side, to her left, and then back again.
Continuity mistake: As Poe Dameron starts his attack run against the Dreadnought we initially see him from the side and his helmet microphone is folded out to the left away from his face. The camera cuts to directly in front of Poe and the microphone is now folded in and directly in front of his mouth. (00:03:25)
Trivia: Mark Hamill's three children have cameos as Resistance fighters.
Continuity mistake: After the scene showing the First Order ships appearing behind the Resistance ships, when Poe Dameron says "It's Snoke's ship. You gotta be kidding me!", the immediate next shot shows him further away and facing a total different direction from Admiral Ackbar. (00:26:30)
Answer: He knew that his blue lightsaber still existed because Rey brought it to him. He chose to show the blue lightsaber because it belonged to Anakin and Kylo Ren was obsessed with it. He knew that Kylo Ren would be angry at Luke wielding a lightsaber that looked like Anakin's and that rage would help keep him distracted. Here is a quote from Rian Johnson regarding this: "He knows that Kylo's Achilles heel is his rage, and so that's why he kind of makes himself look younger, the way Kylo would've last seen him in their confrontation at the temple, and that's why he decided to bring Kylo's grandfather's lightsaber down there - the lightsaber that Kylo screamed at Rey, 'that's mine, that belongs to me.'"