There's no point getting mad about changes George Lucas makes to the original Star Wars films anymore. They're amorphous blobs more than films at this point, and have been since Lucas started seriously tinkering with them back in 1997. And that's okay! The original versions of the films still exist, so you can always cling to that, but the new ones are actually pretty fascinating, if for no other reason than Lucas makes some very strange, subtle changes. We all know (and mostly agree) how weird it was to reverse the Han/Greedo scene (the infamous "Han Shot First!" battle cry of internet nerds for the past 15 years), but there were a lot of changes made, some of which have some seriously questionable logic behind them, and these are some of the most baffling.
This is extremely weird - George Lucas brought back the original actress who played Oola (the dancer at Jabba's Palace that became Rancor food), put her back into the original makeup and costume, and filmed a few reaction shots of her. Virtually all of the footage in the film remains the same, except for a few quick shots of Oola freaking out as the Rancor's preparing to devour her. It doesn't hurt the film, but it really doesn't add anything significant or noticeable to it. And that seems to be the point: to add some supremely minor changes that you won't notice as out of place.
The fact they brought back the original actress, put her in full makeup, and had her re-act the part is an extraordinary length to go to add a few shots no one noticed. To be fair though, she does look exactly the same as she did before, so the effect is as seamless as desired. But this begs the question: Does George Lucas stipulate in actors' contracts that they have to cryogenically freeze themselves for two decades after making a movie in case he wants to film additional reaction shots? I'm not trying to make any wild accusations here, but the evidence is pretty compelling.
It was always a little weird that Obi-Wan was able to shriek like a giant lizard. That's just not a "Jedi thing" we were ever made aware of before or since. And that's fine. I can accept that Jedi can impersonate big lizards whenever they feel like it, just the only time we've seen it was the one time it was useful to do so. Okay. Sure.
The weird thing is George Lucas decided "No, that's not the specific lizard impersonation Obi-Wan would do. Sand people aren't afraid of dewbacks. He would've done a krayt dragon!" Maybe that would've made sense if he wasn't also walking towards then, waving his cloak around like a psychopath. That's what they were running from - the crazy cloak man making lizard noises - not whatever particular species of lizard noise it was. Maybe old people shambling down a hill making dewback noises were known to be kind and non-threatening in the Star Wars universe? I haven't read enough of the Extended Universe books to be sure.
Why is the Empire using multiple giant lizards for transportation on this desert planet? If they were sand people, okay, I'd get it. Sand people aren't the most technologically advanced folk in this universe, and they use whatever is available to them.
But the Empire is not only technologically advanced, they are the MOST technologically advanced organization in the galaxy. They have a laser that blows up planets. They can have their giant Star Destroyers travel at light speed with no issue. But when they're looking for droids on a desert planet, they choose to travel by giant iguana? You have to feed and care for these giant, unwieldy animals that are difficult to control. Even a poor farmboy has a landspeeder. Why wouldn't they use one too? Odds are they have ones that are way better than Luke's, and would probably have tools to help find droids that would not be susceptible to bearded old guys waving their hands. If one or two Stormtroopers were using dewbacks it would be okay (maybe their landspeeder broke down or they were being punished for another terrible day at the shooting range), but the idea of this many Stormtroopers riding fat, slow iguanas is a little weird.
James Earl Jones wasn't credited for 20 years for his role in the first two Star Wars films. It seems strange, since it's become such common knowledge who the voice of Darth Vader is (and likely was back in the 70's as well). This was at the request of the actor himself, since he felt his contribution wasn't significant enough to deserve credit. Still - even watching the credits - you wouldn't assume that iconic deep voice was that of Bristol bodybuilder David Prowse (who was physically Vader). It's not like everyone was scratching their heads for 20 years, asking "Who's voice was that?" Regardless, after 20 years and at no one's request, they figured they'd put the name back in.
Still -- the reason they left it out initially was due to James Earl Jones' specific request. The only reason to put it back in would be if Jones asked them to put it back in, right? Given he still remained uncredited in Revenge of the Sith, that sounds pretty suspect. I can't say for sure, but it's hard to picture James Earl Jones sitting in his home, stewing at the thought that his work wasn't being properly recognized, and calling up George Lucas and demanding his name be put back in. I do kind of understand not wanting to be associated with Revenge of the Sith though.
Yay! Bust out the space bubbly and let's get this galactic party goin', 'cuz the horrible, oppressive Empire is gone! Well, except, uh, it isn't. Sure, a big portion of their strength is gone - and most of the leadership! But if you think every single Imperial officer and soldier was at that battle, you got another thing coming. There are still going to be a lot of Stormtroopers on all of those planets to "keep the peace." A planet like Coruscant would be far more likely to descend into chaos and anarchy than a well-organized planetwide party with fireworks going off. And if you don't think some other Imperial officer is going to take over where the Emperor left off, you're crazy. Plus, wait, not even every ship there was destroyed! There were still some major Star Destroyers in good shape!
And beyond the fact that the Empire is still around and there would probably be rioting and violent uprisings everywhere, maybe not everyone would even think about celebrating - the Empire seemed to be the largest employer in the galaxy by a sizable margin. Can you imagine how many Stormtroopers were required to man the Death Star and a dozen city-sized Star Destroyers? Odds are you had a friend or relative on the Empire's side in that battle, and now they're dead. This is not a time for celebration, everyone. There are like 50 million space funerals to plan.
Okay, even though George Lucas wasn't the credited screenwriter or director of Empire Strikes Back, I like to assume he at least understood the film. Like, on the most basic level of character motivations. He knew why Vader wanted to get Luke so bad (he was his dad, turn the budding Jedi into his Sith apprentice), he knew why Leia wouldn't admit she loved Han (because he was a scruffy nerfherder), and he knew why Luke plummeted when Darth Vader told him to join the Dark Side so they could rule the universe together (he'd rather be dead than join Vader). Adding a terrified scream to that fall seems to indicate he thought Luke slipped or something, instead of stoically sacrificing himself. Why would someone bellow in terror if they were doing this on purpose? Maybe you could argue that, while Luke knew what he was doing, the reality is actually pretty scary. Well, you're probably wrong, since Lucas doubled back and removed the scream.
Here's the really weird part though: the scream wasn't even Mark Hamill's. It was the Emperor's scream from when HE plummeted to his demise in Return of the Jedi. Weird, right? Like they didn't have any recordings of Mark Hamill screaming? If they really didn't, why not have him record one? Or, if they really wanted get a genuine scream out of him, just tell him what his future career as a movie star looked like.