Hello everyone :)
Although I like all SW movies, I understand that there are quite few head scratching parts. Surprisingly there are more of them in OT for me than PT. Anyway here's my personal list (sorry if I missed the explanations):
*NEW HOPE:*
-Leia's lack of emotions concerning the destruction of her home planet with her family, friends, pets, etc. I understand that she has to be strong and all, but she doesn't even remember about it, not even ONCE in entire trilogy.
-Luke and Obi-Wan see nothing bad about leaving a droid who is carrying an extremely important information that can save billions outside the bar, knowing really well that the Stormtroopers are outside, searching. They even met them only few minutes ago, really close to the bar.
-Stormtroopers... Idiots. "Knocking on the door, locked, ok lets go then" thing. To hide from the evil empire... just lock the door. Also what were other troopers doing while Obi-Wan was Force persuading one of them? Just standing without finding anything suspicious. Ok.
-Why did Solo and Luke throw out Stormtroopers armor, their disguise? Because it stinks after trash? After trash compactor all their clothes should stink. Go to bathroom (should be on DS), wash, there you have some disguise back.
-Leia believes that the Empire is tracking Falcon, so... she goes right to the hidden rebel base instead of meeting with an agent, search for bugs, or figure out any other way to send the plans.
-Empire knows that rebels got the plans to the Death Star and know it's only weakness, so.... they do nothing about it. Seriously, why not cover the hole? Place ships over it? Board it up at least? No? Nothing? Ok.
-Death Star has only a handful of small fighters on it, although the ONLY weak point of DS1 is a small shaft that could use protection from smaller fighters.
-Why flying in the trench of DS instead of flying directly to the pipe?
-Obi-Wan is hiding from the empire. Changes his name... but not the last name. And becomes local "weird guy" people know, all while still wearing Jedi robes (as we later saw in Return of the Jedi).
-Obi-Wan said that Jedi were using swords as a weapon. Sword against gun? We see how it works in Prequels, and it worked ok when Luke was fighting bunch of Jabba's people, but they weren't too efficient (even Boba, who was wasted in an extremely stupid way), or one trooper, but what if there are ten enemies with guns?
EMPIRE STRIKES BACK:
-It's been 3 years by cannon and Han still haven't payed Jabba? No wonder Hutt is pissed.
-Why flying in the direction of Empire fleet when the planet is round and space is limitless?
-Why empire is using walkers on a flat surface? They can be good on bad ways, with obstacles, but flat surface? Also they can be defeated by a strong rope. (But hey, they look cool.)
-Yoda is an extremely powerful Jedi, but won't take part in war due to... what? He could use Force in battles, stopping entire ships. Too old? Body doesn't matter, right? Damn, even in prequels Yoda told his old body to f-off and increased it's strength for a short time with a Force to fight. But he won't fught the Empire anymore because... destiny?
-Luke going to Cloud City. Yoda and Obi-Wan don't want him to go, saying that he is not ready and can be killed or turned by Vader. They don't tell the truth about Vader, although it's clear that it is just another possible reason for Luke to join him if Vader tells, what he actually does. Now imagine if Luke wasn't hanging above the shaft, but was cornered instead. The choice would have been between joining the father, only known family he had at the moment, or getting killed. Another thing about it is that Yoda says that if necessary Luke should sacrifice Han, Chewbacca and... Leia?! The "other" last hope? Even if Lucas was not going in Leia is sister way while making ESB, now we are looking at original TRILOGY, which is "flawless". So... kinda foolish, Yoda.
RETURN OF THE JEDI:
-By cannon it's been a year, right? Well, they weren't in a hurry to save Han.
-Why sending the generals of rebellion to save him personally instead of soldiers, or hiring professionals like bounty hunters who seem to have an easy access to Jabba? Honestly I am fine with this one, it's so we could watch the heroes of film having an adventure, not someone unknown, but I add it anyway.
-What the hell was Luke's plan to save Han? Why giving the sword to R2 if Luke wasn't going to give out weapons or anything like it anyway? He even Force chocked Gamoreans, so what's the point of hiding it in R2? It'd be great to have facing Jabba (and of course the rancor). What if Jabba ordered memory wipe for droids? Why sending in Leia to send Han, because even if she succeeded, they still would have to save droids? Bunch other questions, but I think you get the point. Lucas himself admitted that this "plan" was so the movie was longer, because the original script was too short. But hey, we have Leia in bikini, right?
-As I said before, Boba gets "flushed in a toiled".
-Luke knows that Leia has Force power, because she is his sister, which sounds awfully biological (and biology in Force makes fans of originals go crazy, just remember midi-chlorians, that were assigned the status of the Force by them only, but not by a single character in actual movies). And Luke turns out to be right, Leia IS strong in the Force... but somehow Vader wasn't able to sense in when she was standing right next to him earlier on Death Star and in Cloud City.
-The Emperor. Although he is one of my favorite characters in all saga, his actions in Ep.VI are questionable. So he wanted to lure rebels into trap. Good. But was it really necessary to give them real info on the new Death Star? Some fake info would be just as good, as long as they go where they are needed.
With great Force powers that allow him to foresee the future, he surely missed a lot, including a whole army of lethal rocks-throwing teddy bears (which can be a separate thing on the list).
And finally what was his plan to turn Luke into his servant? Turn him to the Dark Side by angering him? Ok, but even if that worked and Luke has turned, and even killed Vader in anger, why would he serve the Emperor and help him destroy the rebellion (friends)? Wouldn't he rather use the dark power (if fallen) to kill the asshole? Or Dark Side suddenly means serving him?