This message has been deleted.

Ok special underwear just for his execution then you think?
It looks like he's about to take part in a gay porn movie haha
Bizarre choice of dress for the hero of a movie?

This message has been deleted.

Probably not yes
He does seem quite keen to slip them off in front of Aura, so probably they are just the usual attire for executions
Shame though as it would be nice to think he had a kinky side…

Well since Flash takes those shorts off as soon as he's revived, I think we can infer that they're not his usual underwear!

Yeah this movie is full of really kinky scenes and costumes like this, the men and the women I'm surprised this isn't commented on more, Flash does have a lot on display in this scene, and he gets to show it all off, walking around flexing wrestling with guards walking upstairs before it ends in the chair. Like a final sexy salute to his admirers.
Another question is are those leather underwear his own underwear he was always wearing or did someone put them on him for the execution?? If it's the first then flash is indeed a kinky guy somewhat at odds with his otherwise wholesome image, if it's the second then someone on Mongo certainly got a lovely job stripping him naked and slipping those on him, presumably while he was unconscious too…
The mind boggles! Perhaps it's best we'll never know for sure…

Agreed, being almost naked would certainly make the gas more effective
Although I'm sure there is also a humiliation side to it too…
Those tight leather shorts don't leave much to the imagination…

It's quite likely related to the fact they're using gas. Barin and Zarkov still have their clothes while awaiting execution later in the movie.

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 the prisoner was 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…

I guess that is the format of executions on mongo, making the victim feel as worthless and vulnerable as possible by being almost naked At least flash gets to show himself off and he does look undeniably delicious in the leather shorts

I think he was clad that way so Princess Aura could feast her eyes on his physique, adding intrigue to attraction she felt for him.