Well I don't know about the reasons behind it all but this was one weird set of images. Totally was not expecting that! Flash prancing around in tiny leather undies and nothing else! OMG? And this is supposed to be a family film suitable for kids?
Watched this last night with girlfriend expecting to be entertained but those execution scenes were just bizarre and almost perverted lol just found myself cringing as Flash was paraded around like that
Having said that gf was glued to the screen and found them really horny so she enjoyed it at least haha
Anyone else find it really weird and rather embarrassing/uncomfortable to watch?

It is a strange sequence I agree, disturbing unsettling, at times quite beautiful and with both sensual and sexual undertones and several subtle hints at what is to come
I think most things can be explained or guessed though. Here are my views
Dungeon helmet: heavy and cruel, designed to keep flash totally in the dark and helpless until the time of his execution. The spikes are probably indicative of a very special prisoner, probably a condemned one with no possibility of pardon. Flash states he can hardly breathe while wearing it, a clue to his forthcoming fate by suffocation in a gas chamber
Clothes removed:
Probably several reasons for this
To make him feel inferior and humiliated during the final moments of his life ie as part of his punishment
To ensure that he is totally defenceless and unable to do anything to stop himself being executed
So that the gas works faster, if his body is bare and exposed it will be absorbed through the skin much faster
Poison gas would probably leave residue on any clothes that he is wearing, hence it makes sense for him to be as near naked as possible
Finally to give him the opportunity to show off his impressive body one final time before his life is over. His final salute to his admirers, Dale and Aura mostly…
Why enter the gas chamber rather than be shot:
Again a few reasons
Resisting the guards is indeed a token gesture of defiance. Flash approaches the steps to the gas chamber and stops, and we see the first flicker of fear in his face as the reality of the situation sinks in. Flash is well aware by now that there is no escape, he is helpless and defenceless, wrists cuffed, totally outnumbered. Yet he remains defiant and heroic to the end and even flexes his pecs a couple of times as if in a final salute to his admirers. He climbs the steps, steady and dignified, glaring contemptuously at his enemies before taking one last long look at the universe, resigned now to his cruel fate. He sees Dale looking down in tears, sets his jaw, turns and walks slowly and sadly into the chamber to meet his doom. This remains the best option rather than being shot as there is still a possibility the chamber could malfunction or something could go wrong to give him a reprieve, however brief
Black hood:
This continues the execution theme, black hood, black helmet, black execution trunks, black wrist cuffs…
The hood covers flash's face for the final time giving him a final brief dignity and hiding any further emotions on his part. It also offers some cushioning and comfort from the head restraint which is lowered onto him (see next entry)
Black cylinder:
This is part of the restraints holding flash in the chair, this one to restrain and control his head and prevent any violent convulsions during the gassing.
Gas release:
Despite the black cylinder Flash's convulsions are strong enough that his head still shakes visibly along with rest of his body. Yes he is not trying to escape at this point but dying. The thick yellow gas is being absorbed through his skin causing muscle spasms and is so incredibly toxic that it apparently ends flash's life in little over 10 seconds, his clenched fists falling lifeless and limp as the gas takes full effect on his helpless body. A horrific but fairly quick way of bringing our hero's life to an untimely end
Or is it?
Gordon's alive?!

1. He's dangerous. Think about it: Ming recognized Flash as a threat after he beat down on his guards in the throne room. Putting a mask on him in the dungeon keeps Flash blind and immobile, and makes him less likely to cause trouble before his execution.
2. As another poster said: the gas works best on bare skin. Removing Flash's clothes deprives him of any protection against the poison. There is also a humiliation aspect to it.
3. Dignity. To be shot resisting is not very heroic. The plot of the movie kinda depends on that not happening too. Shaking off the guards is token resistance. Walking into the chamber anyway shows Flash bravely accepting his fate.
4. The hood is used to give Flash privacy in his final moments.
5. Not 100% sure… I think its just a head restraint. You can see it shaking slightly as the gas takes effect. Given the similarities, I'm surprised Flash isn't more concerned by the thought amplifier in Auras shuttle: an unwelcome reminder of his time in the gas chamber.
6. Yeah that's not trying to escape. That's struggling for life under the effects of poison gas, which is no doubt very painful.

He injects Flash when he revives him with Aura. If what he injects is an antidote at the execution its a two part one. It must be customary to inject something "to help on the way", otherwise wouldn't Ming be a bit suspicious if the doctor suddenly injected something in him he hadn't to others?
You just have to be resigned-
You're crashing by design

'This will help you on your way' suggests something to speed up death, to make the gas work faster. The doctor is obviously expected to be at the execution so this would be what he normally administers. However in this case he presumably injects flash with some kind of antidote to counter the effects of the gas, so that instead of being lethal the gas sends him into a deep sleep from which he can later be revived. (If you look very closely you can see flash breathing slightly when he is lying in the coffin before being revived). Clearly mongo's medical technology is considerably more advanced than earth's, luckily for Flash

What do you think the doctor injected him with?

Having watched the (very detailed) execution sequence again it seems to be there to affirm that flash is a human being. Yes he is a hero but he is no superhero and he is ultimately just one of us. He can be overpowered, imprisoned, stripped of almost everything, humiliated and even executed. This is what the execution scenes are there for, to remind us of flash's humanity and weaknesses so that we can relate to him as one of us. Plus we get to see him almost naked in leather shorts and handcuffs walking to his death. How cool and unusual is that for the hero in a movie?

Maybe it's just me, but I'm sorry I can't see anything artistic or dramatic about the things I mentioned. It's a frankly bizarre scene and it was not clear to me what the heck was going on.

While I love this movie, I think you are looking way to deeply into this scene.
Pretty much all your questions can be answered by this being for dramatic/artistic effect.
You can't palm off a second-rater on me. You gotta remember I was in the pink!

This message has been deleted.

From what I can see that black cylinder you mention is lowered onto flash's head to hold it still while the execution is taking place, to contain his struggles?
I suspect he walks into the gas chamber anyway as it's a nobler more heroic way of going than simply being shot while resisting? He may have been informed also by aura or the doctor that he would be revived later, which would explain why he doesn't put up much resistance or seem particularly bothered by the fact that he is about to die
His clothes are removed to show how defenceless he is and to make him feel worthless and inferior for his final walk to his death. Plus the gas works more effectively on bare skin
Yes he is not trying to escape when the gas is filling the chamber, the time for escape is long past at this point, his body is reacting violently to the effects of the gas, which appears to be absorbed through the skin, as flash begins his struggling before the gas even reaches his facenasty

Yes!^^^^^
I was giving the 'film reasons' which sometimes leave questions like the OP.
Alot has to do with just a look and style as you say. The colors in this film are dizzying.
You just have to be resigned-
you're crashing by design

If you are looking for logical reasoning behind much of what you see in this movie you are likely to be disappointed. The answer to pretty much all of your questions is: it accentuates the strangeness of this alien place and adds to its unsettling nature.
Reality is the new fiction they say, truth is truer these days, truth is man-made

1. Doesn't look very cool to me.
2. But she is a woman and also she is not being executed.
3. Yes but he does not know that.
4. Really? Must be an American thing I guess.
5. A black metal cylinder placed over the top of the hood with a gap for the nose.
6. Okay.

1. Because it looks cool. The bigger question is why the 'lizard' creatures in the dungeon have their eyes
   inside their mouths.
2. Why does Ming's daugther wear a skin tight body suit? Same reason.
3. Because he needs to be killed by the gasa nd not a ray gun so he can be revived later.
4. A hood is kind of an execution tradition. This one is black.
5. Don't remember that.
6. He doesn't try to escape. He is stuggling from the effects of the gas.
   You just have to be resigned-
   You're crashing by design