!!FridgeBrilliance
* The original Mirage Turtles don't seem to have a specific characterization in this film, seeming to be nothing but [[DarkerAndEdgier Grim and Gritty]] {{Bad Ass}}es, until you hear the Shredder call them "The Prototypical Turtles", it makes sense, the Mirage Turtles we see in this aren't exactly the ones from the comics, but the ones from issue #1, explaining why they all don't have much of a consistent characterization.
** Also, the slideshow of TheMultiverse, showing the [[DarkerAndEdgier grim]] but popular '03 episode [[BadFuture "Same as it Never Was"]]. Seems like it will cause continuity problems, until you see that they were actually trying to ''fix'' such problems, since said episode would contradict ''Fast Forward''!
** Turtles '''Forever'''. Indeed, the ''best'' way to say farewell to the Mirage-owned franchise. The TitleDrop down the line just made it even ''better''.
* Amidst those listed on that page (and then some more) who had direct interactions with the Turtles, the ArchieComics and ''UsagiYojimbo'' crossovers all involved Alternate Universes. Utrom Shredder wasn't trying to destroy the ''entire'' multiverse, but only the segment of it which had versions of the TMNT, who all spawned from TMNT Issue #1. (On the other hand, the ''Series/PowerRangersInSpace'' crossover with the TMNT? Took place in the main ''Franchise/PowerRangers'' universe...)
** Also, the fact that TheMultiverse can be destroyed by ''anyone'' just by [[spoiler:killing off the Mirage Turtles.]] In other words, you don't need any superpowers to be an OmnicidalManiac...
** Technically, [[spoiler:they were only vulnerable because Eastman and Laird hadn't finished the first comic yet. Once they did, they followed the plotlines until the end of the series, so while they could still be killed after the series was over, it wouldn't affect the other Turtleverses.]]
* The supposed exaggerated cowardice of the 1987 Turtles is actually FridgeBrilliance. Given their awareness of the fourth wall--they, on various occasions, knew they were in "episodes", and even mentioned that they were the show's title. The '87 Turtles were never afraid where ''they'' came from because they were the main characters of the show, they ''knew'' they would live. Now in ''Turtles Forever'', they were outside of their show and comfort zone- and indeed could really be killed, due to S&P changes and etc.
* Also, the exaggerated cartoonyness of the '87 world and characters. The original series was always cartoony, but the first seasons were actually fairly serious, only to [[{{Flanderization}} Flanderize]] and become sillier and sillier as they show went on (Though not to the level they were here): But even after the show stopped airing, the universe ''continued to get zanier'', til' they reached the level they were at in the movie.
** Actually, the original show had at least a few episodes that were more zany than what happened in the movie. The only real notable thing that seemed out-of-character was [[spoiler: the old toon turtles besides Don breaking down after nearly being killed by Utrom Shredder.]]
*** Refer to the previous bullet point.
**** Also, Old Toon Don was more or less Deus Ex Machina-Man.
***** He pretty much filled that role in the original cartoon though, so it kind of works out.
** It was a bit out of character for them not to take anything seriously too, at least with Leonardo and Donatello.
* If you pay attention to the various characters' color schemes, it's plain to see that [[spoiler: mutant Hun]] is the exact same color as the OT turtles. This makes perfect sense because [[spoiler: ''as he came into contact with the mutagen'']], he was pinning OT Don down to the ground. The fact that [[spoiler: he was in contact with someone who was already a mutant when the mutagen touched him]] may also explain why he wound up looking so drastically different-- spikes and all.
* Why are the 1987 turtles more goofy in this movie than in their show? Well the 1987 show was shown from their prospective - it's obvious they'd see thing more seriously in their world - while the movie is shown from the prospectives of the 2003 turtles - who would find the 1987 enviroment a bit goofy.

!!FridgeLogic
* So...The Turtles and TheMultiverse, eh? What about Dimension X? The Battle Nexus? Are there Ninja Turtles there, too?
** No, but Mikey is '''[[RunningGag Battle Nexus CHAMPION!]]'''
*** This Troper doesn't think Dimension X is a completely separate universe, "just" another dimension that's attached to the "main" 1987 universe. Like how Marvel's Dark Dimension is not a separate alternate universe, but more of a parasite universe.
** Try watching this movie right after ''Back to the Sewers''' last episode. With the Technodrome's rampage on modern New York, you had to wonder...where is the Justice Force?
** Why is Bebop's human form shown walking the streets of the 87 TMNT universe?
*** [[FridgeBrilliance Perhaps as a]] ShoutOut [[FridgeBrilliance to the animation errors in the earlier seasons of the cartoon series]]?
*** Where the heck is Serling? And Dr. Chapman?
**** Probably back in 2105. ''Wedding Bells and Bytes'' shows that Cody fixed the time window again, so he probably used it to bring Serling back into the future after the wedding. Also, it's Chaplin. No idea about him though.

!!FridgeHorror
* After reading on CanonWelding, one realizes that 2003 Shredder would have potentially erased a bit more [[{{Crossover}} than just Turtle universes...]]
** The only other universe lost would've been the VideoGame/RavingRabbids universe. Turtles Forever treats Next Mutation as non-canon, so any universes linked to that are safe.
*** I was under the impression that they merely ignored Next Mutation and the other black sheep of the franchise. Then again, this was back when Peter Laird still owned the rights to the turtles.
**** It's implied that the Multiverse is not something you can just see with your eyes, and that their could be other turtleverses that were never explored before. So whether you like it or not, it's likely that Next Mutation was just as much in danger as all the other worlds were.
* This establishes that if the Ninja Turtles in Turtle Prime die, it will trigger [[ApocalypseHow the destruction of the Ninja Turtles multiverse.]] The Ninja Turtles aren't immortal, and they'll eventually die of age. Think about that...
** Refer to the second entry point on this page. The turtleverse was only vulnerable at that specific point in time, which is why Shredder traveled to that point.
* So they're just going to let '87 Shredder go back to the '87 universe with the upgraded and pimped-out Technodrome capable of destroying universes?
** And EliteMooks
** '87 Shredder is kind of an idiot, remember. Note how he's taunting them with some kind of laughter ray even as he goes into the pimped-out Technodrome.
*** Put an idiot into a shiny room with thousands of buttons activating so many lethal weapons he doesn't know a thing about. How long until he tries them all? If the pimped-out Technodrome reappears on the surface, that universe's New York City is pretty much assured to be razed to the ground in the blink of an eye, while Shredder is still thinking about the laughter ray.
** Knowing 87 Shredder, the most likely thing he'll activate first is the self-destruct.
* Splinter fires a couple of missles at a Purple Dragon mutated into a dog leaving behind some green slime and he was never seen again either as a human or a dog. Splinter '''killed someone'''. It's not surprising since there have been deaths in the 2003 series before, but still...