The last Jedi has left a few unanswered questions. Kylo Ren seemed to perfectly recall himself waking up and Luke holding a GREEN lightsaber up at him (his lightsaber from RotJ). So when Luke and Ren were about to face off in TLJ he should’ve noticed the hilt was Luke’s original blue blade, The same one that him and Rey split in half. Now for those who say “well maybe he generally didn’t look at the hilt”, I perfectly recall him noticing it in the force awakens. It was the first thing he said when Finn pulled it out hence probably one of the first thing he looks at.
Another thing I sort of picked up on is, Maz has been alive to see the PT-OT-ST so I expect she would no who and how many people know how to break onto The Supremacy. So where did this guy in prison come from?Now these are nitpicks. A person’s focus shifts. When their thoughts are intently focused on one thing, they may miss another or care more about the main thought in their head (such as OMG, Luke is here). Maz may be old, but that doesn’t mean omniscient. She presumably named the person she thought capable and trustworthy and locatable, among any other unknown characteristics. It’s not like there can’t be anybody else in the galaxy who is competent at hacking.
It may be a nitpick but that does not mean its entirely wrong. I recall Maz saying their is one other person and if you want to get onto Snokes ship he’s the one. Now she may not know of the other one where you are completely correct. This all goes without saying the man in prison (DJ) is also a master codebreaker.