Marshawn Lynch, Lance Armstrong Wield Massive Flamethrowers On 'Stars On Mars'

Marshawn Lynch and Lance Armstrong turned the heat all the WAY up while out on "Mars" ... wielding some massive flamethrowers -- and the video of them chucking fireballs is awesome!!!

The dudes got armed with the weapons for a challenge on the latest episode of the Fox show, "Stars on Mars" ... and the former athletes sure seemed to love being fungus-killing pyros for a few minutes.

Check out the clip ... as Lynch went to extinguish his foe with a massive blaze, he channeled his inner Al Pacino -- screaming out, "Say hello to my little friend!"

Armstrong, too, handled the big gun well ... though he did note the thing was hot as hell!!

It was a cool change of pace for the guys ... because in last week's episode, some of the show's contestants were seen really feeling their separation from the real world.

In fact, Ronda Rousey actually broke down in tears while FaceTiming with her fam.

But, everyone seemed to enjoy the most recent hot challenge ... especially Lynch!!