In fact, Kenshiro is so badass that the Mook's face mask was already smashed! It's also why the mook's head exploded instead of Kenshiro's; Kenshiro elbowed a Pressure Point in his face that set up a hilariously timed delayed reaction.
His original counterpart in the manga was at the receiving end of the Zenkai-Ken. Kenshiro then puts the poor sap in the hole with only his thumbs.
From the same episode, Ken burying the saw (which he'd just been given and ordered to cut a guy's head off with) into the Mook's head.
-"Yes... But not on me..."
When Rei does this in the 1986 film, the mook experimentally taps the saw now buried in his head. Giggle fuel!
Mook: Nah, I was talkin' about the other guy.
Rei: Silly me, what a foolish mistake.
Mook: I got a splitting headache...
Rei: Oh? *Moves the saw a bit, killing the poor guy.* Better now?
The Humiliation Conga that Jyuza dealt to Raoh and his army. Outsmarting Raoh with a fighting style he literally just made up, stealing Raoh's horse and just to rub salt in the wounds, Jyuza slaps his own ass telling Raoh that he can "kiss his ass".
Kenshiro shoved one poor miniboss into a cannon, then shot it through a hot air balloon, then exploded when he landed (the scene is 9:10 minutes into the video). Speaking of that, Nanto Human Cannon technique does not look like it is a serious technique, but just some ridiculous child's trick playing the name of Nanto already.
Also, as mentioned in Crowning Moment of Awesome, Kenshiro blowing up the tank!
Any time one sees Rei cutting, slicing, cubing or julienning a mook, it is to giggle madly. Especially since this is usually accompanied by a helpful TV split-screen effect that we see is not an effect at all.
Sometimes, he ends up swiping them so fast that the momentum actually causes the pieces to swap to the next guy over. In sequence.
Kenshiro's climactic battle with Boss Fang, who is using the Hua Steel Armor technique to make his skin like steel, comes to an abrupt halt as Kenshiro strikes a pressure point that returns Boss Fang's skin to normal, then bashing him with a rusty I-beam. The first two blows are positively brutal, but the comedy comes from the resulting image of a giant, muscular, fur-clad barbarian king cowering and shrieking as Kenshiro beats him repeatedly with an iron girder that otherwise seems to have all the impact of a foam pool noodle. The capper is when Boss Fang proves to be a Dirty Coward and throws one of his many sons at Kenshiro to try and hold him off. Kenshiro responds by holding up the steel beam so that the Fang Clan mook runs facefirst into it, then casually drops the beam onto the mook after he falls off it. It's an oddly cartoonish moment in an otherwise serious fight.
An earlier match with the fang clan is also pretty funny. Right from the moment Kenshiro hits their leader in the eyes with a pair of food cans.
This one comes from the French dub, and it kinda falls under both Black Comedy and Crosses the Line Twice: instead of committing suicide, Yuria apparently falls of Shin's palace by accident, because he didn't instal the railings yet. Shin then responds, "Bring me the architect; it's his fault she died!"
Ken defeats Warden Uighur's whip attack, sending the warden's whips back into his face... tied up in a bow.
Raoh's lieutenant Galf uses his loyal dog Seki to decide the fate of his victims. However, when struck by Kenshiro, Galf tries to get Seki to stand by him as he's about to die. Seki sensing that things are about to get messy, flat out pisses on Galf and abandons him.
Shin is very rarely shown fighting anyone. When he starts slicing people with his Nanto Seiken techniques, his deep voice becomes replaced with a high pitched battle cry akin to the squawking of a bird.
In Ten no Haoh, when Raoh and his entourage make their way into the king's palace so that Raoh can kill him and take over, they're masquerading as entertainers with Raoh as the koto player. When asked to play the koto, he responds while not having a facial expression: "I will play the koto!" *smashes the koto on a pillar* "I cannot play the koto!"
When Kenshiro confronts Alf, Ken makes light of him by asking who he's supposed to fight against. The only other guy in the room is a 'useless mook' (Who is actually Shachi in disguise), so Alf is greatly offended.