Adaptation Displacement: Most people remember the 1987 series. The comic book that inspired it? Not so much. This has been partially alleviated due to the advent of the internet in the 2000s, and later shows using elements more explicitly from the Mirage comics rather than the 1987 series, although the shows remain far more famous.
Alternative Character Interpretation: 1987 series: This theory seems to have arisen for some... is Irma chasing after guys really her desperation in nabbing herself a man, or, is it an act of desperation to cover up her being a closeted lesbian?
Americans Hate Tingle: Ironically, TMNT has a rather weak Japanese audience. TMNT enjoyed a few years of popularity when it was first brought there in the early 1990s, but it quickly nosedived and failed to find any continuous success due to lack of interest. The Japanese dubs of TMNT shows tend to be short lived and the Imagi movie was put straight-to-video.
Base-Breaking Character: Venus de Milo. Most fans see her as a Replacement Scrappy for April O'Neil, but some fans think that she is an interesting concept and would like to see her return in one of the current Nickelodeon-helmed adaptations. It's particularly telling that even the franchise's creators have differing opinions on her: While Peter Laird is well-known for outright despising the character, Kevin Eastman has gone on record to say that he likes the character and hopes for her to someday make a comeback.
Better Than Canon: Some fans who do like Venus de Milo tend to make her more well written, give her flaws and a different backstory.
Some works. But fans try to forget Next Mutation, the third film, and the 2018 series.
How most fans of the 1987 series treat the Red Sky seasons (though some are fond of season eight).
Friendly Fandoms: TMNT fans and Usagi Yojimbo fans get along pretty well, thanks to the fact that the creators are friends in real life and have had their characters cross over in each others' series; Usagi has also guest-starred in every animated TMNT adaptation to date.
In 2016, a short called "Don Vs Raph" by Jhonen Vasquez involved Donnie and Raph fighting each other with trivial contests. In 2018, there was a Splatoon 2 contest themed after who the best Teenage Mutant Ninja Turtle was, with Pearl siding with Raphael and Michelangelo, and Marina with Leonardo and Donatello. The finale of the Splatfest was Raphael vs Donatello (which Donatello ended up winning).
Replacement Scrappy: Any version of April who is not the news reporter per the 1987 series or the live action movies is considered this to some. Except for the original April who is neither a reporter, a replacement, nor a Scrappy, making later fans view this version of the character as basically Early Installment Weirdness.
Try watching the Christmas Special, We Wish You a Turtles Christmas without laughing.
About 90% of the 1987 series.
Special Effect Failure: Any live action Ninja Turtles production that wasn't a movie, save for the third one. "Turtle Tunes" and "We Wish You a Turtles Christmas" are the worst offenders in this regard.
Fans of the original Mirage Comics dish on the 1987 series for "selling out". Fans of the 1987 series say this about the 2003 version and its more serious tone. Fans of the first five seasons of the 2003 series will scream obscenities at Fast Forward due to its radical shift in tone, setting, and look. This was Lampshaded in Turtles Forever when the 1987 turtles and 2003 turtles arrive in the 1984 (Mirage) universe. The Mirage Turtles there call the others 'sell outs' though they eventually settle their differences.
As per tradition, 2018 is being blasted with this as well, most prominently for Splinter's characterization as well as Raphael being the leader at the beginning.
Uncanny Valley: Usually a problem with the Turtles in Live Action Adaptations, most notably the cheap Coming Out of their Shells Tour and We Wish You A Turtles Christmas Special. Splinter often looks even worse.
The 2007 CGI movie, on the other hand, makes the turtles look quite nice, but the human models have been accused of this.
The costumes in the Operation Blue Line promotional video — which was about a light rail service that went from Los Angeles to Long Beach, and released only in California for free — blow everything else out of the water.
The original comic is a spot on pastiche of Frank Miller's work circa the early to mid 80s (mostly Ronin and Daredevil); the writers being big fans. The best example is The Foot, who are based on Marvel's The Hand (get it?).
Also compared Daredevil's master (Stick) to the Turtle's master (Splinter). Both origins involve a truck of toxic waste too. The first issue starts with a page-by-page rip off of the toxic accident that created Daredevil, up to and including the "kid saving an old man and getting blinded" bit. If it weren't for their divergent timelines or the copyright being owned by different companies, the idea was that the blind kid is Daredevil and the canister that created him also created the Turtles. Marvel actually did have the rights to the Turtles comics at one point, but they were set in a separate universe, so perhaps the Turtles are part of the Marvel multiverse and in this one, Matt Murdock never became Daredevil and just became a blind kid.
A few elements were cribbed from X-Men as well; Leonardo was Cyclops and Raphael was Wolverine; and when Krang and Shredder◊ appear together, they seem eerily similar to Mojo and Spiral◊. While the X-Men have gone onto prominence in their own right, for a while they were less known to the public than the Turtles.
Tropes that pertain to the 1989 Nintendo Entertainment System video game:
Anticlimax Boss: After all the crap it takes to reach him, Shredder is a relative pushover due to the fact that he's the only boss in the game that can be knocked back. Players who get him in the right rhythm can just keep smacking him without giving him a chance to counter.
Breather Boss: The Big Mouser at the end of level 4. It's completely stationary, and its only attacks are occasionally firing an eye laser and dropping regular mousers. If you stand under it with Donatello and spam your upwards attack at its weak point, neither of these will ever hit you.
Demonic Spiders: It's bad enough that there are respawning enemies but there are some enemies that really make this game unfair and annoying to play.
The worst enemy that you will encounter in the game are the Flying Spacemen armed with laser guns in the later sections of the Technodrome. They appear and move so quickly that you almost can't react to them without getting hit. What's even worse is that there are sections of narrow halls that make getting shot or running into them an inevitability. It also takes two shots from the Scroll, the best sub-weapon in the game, to kill them.
The spider robots in Area 5 are notorious for making climbing sections a total pain since they move fast towards you and you're completely defenseless while climbing the wall.
The large porcupines in the underground sections of Area 5 are cheap and unpredictable as they jump and attack in completely random patterns, making it hard to not get hit by them.
Ear Worm: The overworld music for Stages 1 through 5, building theme 1 and the boss music are popular choices.
Game-Breaker: The scroll weapon makes quick work on most bosses. However, it's extremely rare and can be replaced by other subweapons.
Also Donatello, considering that his bo staff had absolutely absurd offensive power and range, which made most boss fights pretty trivial.
Good Bad Bugs: The North American MS-DOS version has a required jump that is literally impossible to accomplish. However, you can still beat the game without cheats, if you do a sequence of extremely strange actions (although you still skip the rest of that level). If you have rope, there's a place on the overworld that you can walk, which triggers the use of the rope. Suddenly, you're using the climbing animation on the overworld. If you now enter a specific building, you will fall through the floor into a glitched level. You might end up dead, or the game asking you to insert another disk, or just trapped in a broken level, but there is a chance that the game will instead teleport you to the beginning of the next level. 
Porting Disaster: The North American PC version to say the least. The third stage cannot be completed without cheating or a very strange glitch because of a design flaw in one of the sections in the sewers. The jump is impossible to make because of the ceiling being shorter and the platform on the other side missing a block. The UK Teenage Mutant Hero Turtles corrected this by extending the platform, but retained the other design decisions that made many aspects unintentionally more difficult.
As shown by James Rolfe, the Commodore 64 version is definitely inferior to the NES version, with two of the biggest problems being the slower gameplay and that jump and attack share the same button.
The original NES game is infamous for being Nintendo Hard (its PC port is even worse), and the ones based in the most recent cartoon are underwhelming. The beat-em-ups by Konami, however, are generally considered classics of the genre, making them an aversion.
The pinball machine game is often held to be a generic, boring pinball game.
Despite hopes due to being developed by PlatinumGames, Mutants in Manhatan ended up being another case due to repetitiveness and lackluster level design.
Surprise Difficulty: Sure, the game's reputation precedes it nowadays, but back in '89 when the game dropped, at the height of Turtlemania... let's just say there were a lot of pissed-off youngsters.
The first few seconds of the intro music sounds incredibly similar to "Stone Cold Crazy" by Queen.
The Area 5 overworld theme resembles the opening riff of The Beatles' "Come Together".
That One Boss: The Technodrome boss in level 5. First of all, level 5 is That One Level in itself due to the fact that the boss is randomly placed at the end of one of three caves. As for the Technodrome itself, the prong in its front fires a powerful lightning beam that covers a third of the play area, making it nigh impossible to approach without using secondary weapons to destroy said prongnote or exploiting a glitch with the pause menu that makes the bottom half of the beam disappear. On top of that, it also has two turrets on the body firing a constant stream of bullets at you, as well as the open compartment at the top which spawns infinite Foot Soldiers to further hinder you. All of these have to be taken out if you want any chance of safely attacking the eye at the top, which is the boss's true weak point. Hope you packed a lunch!
The notorious dam level, dubbed "That Damn Dam" by some, and some fan theories persist that this level was what turned famed movie critic Roger Ebert off of video games (he played to this level, which allowed him to spot an inaccuracy in The Wizard.) The dam level owes its infamy to the following factors...
It's a Timed Mission. You are charged with defusing eight bombs under a time limit, with annoying sea life everywhere trying to inhibit your progress. Failing to defuse them all before time runs out will result in a...
Non-Standard Game Over. It doesn't matter how many turtles you have left; you fail once, and it's all over. Luckily it's the only game over of its kind in this game, since according to gamers who managed to pass this level, the game gets even harder.
Then when you get to the later levels, it doesn't get any easier from here in. The third level is a maze where you have to find the correct solution to it. The fourth level, the Foot Air Base, will have you pulling your hair out. It's not only another maze, but it's also full of dangerous hazards, including liquid flame pits in some of the underground tunnels that will kill any turtle instantly on contact. Thankfully, the boss of the level itself isn't too difficult.
The Abandoned Warehouse is the fifth level and it's quite difficult due to many factors: The enemies in the caves are Demonic Spiders, and one of the three caves contains the boss, the Technodrome Defense System. If it doesn't, it brings you to an empty room, and you're forced to backtrack to the beginning of the cave. The game generates it before you enter the level, and there's no clear indication on which cave is correct until you either find an empty room or the boss. To worsen it, the enemies respawn when you exit the empty room, so you'll inevitably have at least one turtle with low health.
Tier-Induced Scrappy: Raphael, oh dear god Raphael. The main reason for this is because instead of thrusting his sai daggers forward like he should, he just sticks out his arm and spins them in place which means he has absolutely no range on his attacks as opposed to the other turtles who actually have decent range with their attacks. This means it's a good chance you'll take damage while trying to damage the enemies. This game is alreadyNintendo Hard, but using Raphael as your main character takes this Up to Eleven and falls somewhere between Self-Imposed Challenge and outright Unwinnable.
And You Thought It Would Fail: Many major studios such as Walt Disney Pictures, Columbia Pictures, MGM/UA, Orion Pictures, Paramount (whose parent company Viacom would acquire the TMNT property in 2009) and Warner Bros. turned down the first film for distribution as they were worried that despite the popularity of the 1987 series and the toy line the film could potentially be a box office disappointment like Masters of the Universe was just a couple years prior. The film finally found distribution roughly halfway through the initial production via the then small and independent production company New Line Cinema which at that point had been known more for distributing low budget B movies and arthouse fare.
Anti-Climax Boss: The Turtles finally confront Shredder in the first film and he spends roughly three minutes defeating them with little difficulty. Then Splinter appears and defeats the Shredder in one move.
The main theme for the turtles in the first two movies.
The build-up music for the climax in the first movie.
Critical Dissonance: None of the films have gotten positive enough reviews to warrant a fresh rating on Rotten Tomatoes, although the first film, while not considered a work of art, has a much more positive and enjoyable reception from audiences, particularly among fans of the franchise.
Ear Worm: "Turtle Power" by Partners In Kryme. Although it incorrectly cites Raph as leader, it's still a rap of the highest caliber. It would be reused in the soundtrack CD of the third movie. Spunkadelic's "9.95," though to a much lesser extent, is also catchy in its own right, and would be reused in the trailer for the second movie.
Franchise Original Sin: Teenage Mutant Ninja Turtles (2014) often gets flack for making April the focus of the story, though the film still centers around the turtles. The Turtles personalities are well done, but they don't get much character development. Lacking Casey Jonesnote who was MIA in Secret of the Ooze and putting in a villain (Eric Sacks) who had nothing to do with any of the comics or cartoons prior to that point was a mitigating factor too. The thing is that this problem can be found all the way back in the 1990 original. As pointed out by CinemaSins, Raphael is the only who gets a character arc of some sort, Leo gets some, and Donnie and Mikey don't get any at all. Plus, Danny, a minor character, had a sub-plot that while did not take over the whole film, was an odd decision. The reason why it wasn't noticeable back then was due to it being the Turtle's first film, the hype surrounding it, and a well written story with great practical effects and action scenes. The sequel, Secret of the Ooze, tried to fix the character development issue by putting the focus on Donnie's arcnote When the turtles find out they were created by accident., but it never really goes anywhere. Turtles III and TMNT (2007) both featured villains that had nothing to do with the comics or cartoons, albeit, the latter had Karai with hints of Shredder returning in a sequel that was never made. Tatsu wasn't in any prior media either, acting as a stand in for Karai, but he was the right hand man to Shredder, so that was okay. Karai was still obscure at the time unless one read the original comics, so that was understandable. Ooze had Tokka and Rahzar as expies for Bebop and Rocksteady, because Peter Laird and Kevin Eastman did not want them in the film. Teenage Mutant Ninja Turtles: Out of the Shadows, the sequel to the 2014 movie, is fixing that by dropping the Eric Sacks character entirely, adding in Bebop, Rocksteady, and Baxter Stockman. Villains that have appeared in the cartoons or comics. Also, the turtles themselves are going to be the main focus of the story and receive character development just like in other media..
Hilarious in Hindsight: Any sports fan over the last decade who's read the stories on steroid use can now look back on Raph's comment on Casey's Jose Canseco bat with a whole new meaning.
It was a two-for-one sale.
Donatello gets ragged on by his brothers for trying to make the word "Acapella" sound cool. Years later Eminem finishes what Don started, by using that word and the meaning behind it in a crucial moment against Papa Doc in 8 Mile .
In one fight scene, Casey defeats Tatsu by swinging a golf club at him, and he promptly kisses the club, saying, "I'll never call golf a dull game again." There's a ninja game for the Atari called Ninja Golf.
Kids nowadays, watching the scene with the teens in the warehouse, may have trouble understanding what is so subversive and rebellious about using an indoor skateboarding park, playing an electric bass, spraypainting a wall clearly set up for the purpose of spraypainting, playing arcade games, and doing a little recreational gambling. As an '80's kid, this troper was initially quite shocked by their decadence; now it seems that the least horrifying thing in the '80's (Regular, or Menthol?) is the only bad behavior in the entire scene.
Do you like penicillin on your pizza? (Proceeds to hum "Taps".)
Narm: The numerous G-rated swears in the first film can be hard to take seriously. Raphael screaming "DAAAAAAAAMN!!" is especially comical.
Narm Charm: Those who like the fact that the original movie allowed the characters to swear at all revel in these scenes, regardless.
Retroactive Recognition: The gang member who snitches to the cops at the conclusion, is a young Sam Rockwell. He also delivers the line "Regular or Menthol" when asked if he had smokes.
Special Effect Failure: A clearly human hand swings in front of the camera as Donatello does a spin on his skateboard, there's a moment where you can clearly see a microphone cord dangling from Raphael's shell, and another where you can see the face of Donatello's actor peeking though his mouth.
Visual Effects of Awesome: The animatronic suits and puppets from the first two movies, especially the first, still look unbelievably good even today; they should, since they were created by the Jim Henson's Creature Shop and were the predecessors of all the current systems used for their full-bodied animatronics.
What an Idiot!: The two footsoldiers that tried to drown Donatello in a fishtank. The look on his face while underwater screamed "How stupid are these guys."