[Aaronardo]

The biggest missed opportunity for me was Tiger Claw's potential character arc. I know I wasn't the only one seeing foreshadowing for Tiger Claw betraying Shredder starting at the end of Season 2. It was one of the only parts of Season 3 that got me somewhat excited.

Think of it, starting with Vengeance is Mine, where Tiger Claw is in disbelief that Shredder would put his own daughter's life on the line in the name of revenge ("You are more ruthless than I thought... mutating your own cub..!"), and then talking back, defying Shredder even, after Karai is mutated. You don't see him again until the opening scene of The Invasion, where we get another sign of Shredder's increased obsession and even insanity ("Nor do I (care for the human race)"). In the same scene, we see Tiger Claw thinking outwardly once again.

As the show continued, we saw relatively little of Tiger Claw in Season 3, but his two biggest roles certainly continued this trend. In Return to New York, he questioned Shredder as to why their alliance with The Kraang continued after their enemies were defeated, and in a rather alarmed tone. Finally, in Annihilation: Earth, after Shredder killed Splinter in favor of saving the world from being sucked into a black hole, Tiger Claw blatantly calls him out on it ("Shredder! What have you done?!").

Now, obviously, because of the way the series played out, those final events of Annihilation: Earth didn't even happen, and so Tiger Claw being pushed to the edge at that point didn't really happen. But all the foreshadowing before was still there.

I could just be seeing things that aren't there, but this sounds a lot like foreshadowing a plotline where Tiger Claw gradually realizes Shredder's increasing obsession and insanity and betrays/leaves him, still, however, an enemy of the Turtles. But clearly, in Season 4, he acted more like a mindless servant to Shredder and in Season 5 is trying to bring him back from the dead. Completely missed potential for a great plotline that could've made Tiger Claw an especially unforgettable character.

Also, unpopular opinion that really is just a nitpick, but they missed out on the opportunity to recast Leo as ANYONE but Seth Green.