When carrying Sonic around, Tails puts on a very strained face. In prerelease footage, it seemed that Tails reacted with shock if Sonic started moving while he was in the middle of his yawning Idle Animation. In the final game, it's seen that Tails jolting awake is part of his Idle Animation... which might be funnier since Tails becomes aware that he started sleeping on the job.
The Orbinauts in Studiopolis Zone get increasingly worried expressions on their faces as you bust their bumper barriers. Once they're all gone, they look so defeated one could almost feel guilty about finishing them off.
In the opening animation, when Sonic's fighting Heavy Gunner in Studiopolis, Knuckles looks into a warp ring to see the commotion, only to be knocked away with a face that just screams "OH NO". And as Sonic leaps to the air, he can be seen hanging on the same ringas it's spinning.
After the Death Egg Robot is defeated, Sonic and Tails watch Eggman on the wreckage giving orders to the Hard-boiled Heavies. They seem like quite quirky guys, as Heavy Shinobi juggles the Phantom Ruby on his head and Heavy Rider races around atop a Motobug with bloodshot eyes.
When starting Chemical Plant, a cutscene plays where your character of choice gets splattered by chemicals just before starting the stage. No matter who you choose, their reaction is priceless. Tails even had a Dummied Out animation for this cutscene where he dries himself off with his tails. (In the final game, he simply looks up.) Plus brings this back with a slightly different animation.
Sonic's expression over the Dr. Robotnik's Mean Bean Machine boss fight is priceless. He's completely thrown off-guard by the whole situation, like he's thinking the same thing as the player, namely "Did I fall into the wrong game?!" or "Where the hell am I?" Even more hilarious if Tails is with him, since his sprite remains normal and his Idle Animation kicks in where he starts falling asleep.
Tails also looks quite confused, if a little less so since him being a lot smarter than Sonic means he's probably more familiar with Puyo Puyo than Sonic was. It's a battle of the geniuses!
Knuckles' expression is just as hilarious. It's less "Where the hell am I?" and more "What the hell am I doing?"
The boss fight, in and of itself, is also funny in its simplicity: Eggman SUCKS at Mean Bean! And he was the Final Boss of said game!
Eggman's lack of skill only gets funnier when you apply Fridge Brilliance: it's been twenty-four years since Eggman's last had a crack at using the Mean Bean Machine to fight anyone; it only makes sense that Eggman would be extremely out of practice when he decides to bring it back to battle Sonic!
Just the fact that Eggman was considerate enough to lower the controls so all of the playable characters can use it.
Sonic's later appearance as a guest character for Puyo Puyo Tetris 2 in its bonus DLC makes the entire thing even funnier, as it gives the impression that Sonic enjoyed the Mean Beans enough that he snuck into the mainline Puyo games to play it.
In Mirage Saloon Act 1, Sonic, Tails, and Knuckles are flying over the desert in the Tornado. But the Heavy Magician suddenly swoops in and knocks Knuckles off. Sonic's Idle Animation kicks in right after this, suggesting he's quite annoyed. It's even funnier if you're playing as Knuckles, where the music just stops as it happens.
The shrink ray gimmick returns in Metallic Madness Act 2. If Tails is "dead" while Sonic passes by the beam that reverts him back to normal, Tails won't revert, leading to a tiny Tails following Sonic around. The inverse can also happen, letting a normal-sized Tails follow a tiny Sonic around. The PC update fixed this and the AI controlled characters change their size depending if you're normal sized or not.
In yet another case of Bond Villain Stupidity, Dr. Eggman finds the most interesting way to confront the aforementioned tiny Sonic is to drive a gashapon dispenser machine called Gachapandora. Several miniatures of the rides he had in Emerald Hill and Marble come out of capsules to attack you, along with Amy dolls sporting Tails Doll's vacant eyes and antenna which try to hug you to death (by explosion). To cap it off, once the dispenser runs out of stuff, you must spin the crank one last time for Eggman himself to slide out.
One of the Medallion unlockables is "& Knuckles" mode, which puts Knuckles by your character's side even if your character is already Knucklesnote So you could say you're playing Knuckles & Knuckles. Because of this, it's possible to have THREE Knuckleses appear in the normal ending (the playable Knuckles, the AI-controlled Knuckles, and the NPC Knuckles driving the escape vehicle).
The ending is also hilariously cute, as Knuckles reads his own embellished version of the game's events, aptly titled "Sonic Mania & Knuckles", to the animals while Sonic and Tails just look at him in confusion and doubt, all while a comical version of "This Horizon" plays.
In Lava Reef Act 2 as Knuckles, you actually revisit the Hidden Palace Zone from Sonic 3 & Knuckles as Heavy King moves to grab the Master Emerald. Cue Knuckles actuallyremembering the last time Eggman stole the emerald with a Thought Bubble (that resembles the Mega Drive comic's art style) before flipping out and smacking him right off of the Emerald.
And the normal boss fight for the act when playing as Sonic and/or Tails isn't a slouch either: Heavy Rider, riding a frenzied and pumped-up Motobug named Jimmy on top of a platform that's rising higher and higher, pretty much zooming back and forth trying to smack you with her flail. Except occasionally she takes a high ramp, and jumps clean over fire-spewing hazards while confetti and the cheers of an unseen crowd go out, making the boss like less of a knight and more of a stuntwoman. In what's also a moment of heartwarming, Jimmy the Motobug is named after a rom hacker who made the Motobug in Sonic 1 hack.
In a simultaneously intimidating and hilarious move, the Phantom Heavy segments of the final boss fight don't change Heavy Rider at all. Instead, she channels the power into Jimmy to turn him into an unfathomably angry souped-up chopper cycle
Kind of an unintentional funny, but in older Sonic games note With the exception of Sonic 1, dropping a monitor on yourself resulted in getting crushed. In Mania, doing so just causes the monitor to bounce repeatedly on the character's head.
After defeating the standard final boss, Dr. Eggman's "Phantom Egg" battle suit cracks in half. The literal Egg-yolk-man then falls out and starts flopping in frustrationlike a baby.
Additionally, in said boss fight, you can collect rings in two of the other areas that it warps you to in between charges. If they bring you above 100 rings, the extra life music jingle plays and interrupts the intense final boss battle theme, then it goes back to that as if nothing had happened. Way to lighten the mood.
Deflecting the Heavy Gunner's missiles back at him results in a hilarious Oh, Crap! reaction from him. It gets even more humorous when he's on his own and you deflect the final missile at him, leading him to fly away from his own helicopter as it crashes on the ground.
Funnier still: When you defeat the boss, the giant monitor in the background displays an "off the air" test pattern. The numbers on that pattern's bottom-right corner are the date (July 22nd, 2016) of the infamous livestream during which this game was announced. To drive home the point, the game plays a specific noise in the background — the omnipresent buzzing that plagued said livestream. Guess that really is the sound of 25 years of Sonic!
Also, just before the aforementioned buzzing sound kicks in when you defeat Eggman, the chicken badnik who's giving the weather report gives the biggest They don't pay me nearly enough for this look.
In Mirage Saloon Act 1, the goal sign at the end lands on the the bottom of the screen, making it appear to be floating in midair. However, the transition to Act 2 reveals that the sign landed directly on the Heavy Magician's hat.
You can get a Trophy/Achievement for riding boats in Hydrocity Zone. The description for it? "We really like boats".
Another bit of unintentional funny involves activating a crumbling platform on Green Hill when a Moto Bug is on that piece of land. It'll stay suspendedfor a second before actually falling. Sadly this seems to have been patched out as it was likely unintended behavior.
There's (or rather was) an Easter Egg in Hydrocity Zone where, if you input the Sonic 3 & Knuckles Level Select codenote left, left, left, right, right, right, up, up, up while holding onto a hook, you will hear a ring sound. The next time you're grabbed by a speed booster, the regular sound effect will not play. Instead, it's a voice clip of Video Game Dunkey mimicking the booster. Hear it for yourself. It was sadly removed in an update, as it was likely that the devs had snuck it past Sega's approval process.
A rather obscure one, one Dummied Out mechanic in the debug mode (although it could only be found in the PC version) is a Love-Tester Slot Machine which pairs your currently played character with other characters. You get bonus points for getting the best combination for each character, and zilch for the worst. If you forget that the machine is made from Eggman's perspective, you might get caught off guard when testing it as Knuckles, as he has Eggman as the best pair and Sonic as the worst.
One of the comments under the linked video above has another amusing interpretation: the pairs are not from the tester's perspective, but from the character chosen by the machine. Sonic has Amy as the best choice because she's obsessed with him (and he's utterly disappointed about it), Tails has Sonic because they're best friends (and he's slightlyoverexcitedabout this), both of them have Eggman as the worst choice because of how many times they ruined his plans in the past, Knuckles has Eggmanas the best choice (to his own confusion) because he's easy to manipulate, while Sonic is the worst (pissing him off) because the doctor wants them to remain rivals to serve his goals.
The Continue? screens from "No Save" mode for Tails and Knuckles are funny. Tails looks like he's ready to doze off (and is startled when you choose to continue) while Knuckles throws a tantrum and stomps his feet (and clenches his fist if you choose to continue). If you've downloaded the Encore DLC, Mighty's screen adds to the humour; he is facepalming throughout and choosing to continue makes him breathe out a heavy sigh, as if he knows that Continuing is Painful.
After defeating Metal Sonic in Stardust Speedway in Sonic Mania Plus, the Phantom Ruby looks ready to be taken out of Eggman's hands… only for a Dango* (the pill bug-like badnik) to randomly appear and knock it offscreen before the player can get to it. It then hops in place for a few seconds before rolling away, almost as if it's laughing at you.
The all-Emeralds ending to Encore Mode: As your two current characters watch as the Phantom Ruby opens a portal that starts sucking everything in, Eggman literally tiptoes away and steals the escape car from the normal campaign. It looks like he's about to make a clean getaway… until the five heroes zoom by in their Super modes and bop him into the portal to suffer a fate unknown.
The Stinger that plays once Encore Mode is completed. The whole gang kicks back with some sundaes at the Mirage Saloon bar and pose for a group shot, only to be surprised (and photobombed) by the saloon's bartender — Heavy King!
When Ray is crossing the hang bars in Flying Battery, rather than simply pulling himself along with his hands like the other characters, he uses his hands and tail to flip across them. It looks funny, awesome, and adorable at the same time.
◊ Tails
