Awesome episode. All of the cutscenes explaining how Tiger Claw got back to this dimension were great. The original cartoon turtles, The Triceratons, and the one creature in the background of one of the scenes reminded me of Famine from the Archie series. So Tiger Claw is one tough dude. I like him even more now than I already did in the first episode(s) he was in. Definitely my favorite Nick created character.
Tiger Claw is just brutal at times. He throws Casey off of a tall building for the heck of it. It also shows that his revenge has clouded his judgement a little bit. In "The Manhattan Project" he agrees with Karai and stops Shredder from killing a weakened Splinter. But in this episode he mentions "I didn't come here for honor" in talking about interrogating Mr. Murakami. I also like the threat that Tiger Claw smelled the turtles down in the sewers. I don't know if that will actually pay off or not but it was at least cool to threaten it in this episode.
The final fight was also very awesome. Tiger Claw in the meat locker reminded my of the scene from Predator 2 which is interesting since I thought The Newtralizer reminded me of the Predator a couple of weeks ago. I thought it was great when Tiger Claw fought with his sword and one of Raph's sai. The final fight was just amazing.
I liked that in this episode we saw one of Casey's stash places where he hides his golf bag full of his equipment. And I really loved the line from Casey "Okay, Cat-Man-Dude" which was a great reference to us Archie fans (whoop whoop!!) of Katmandu. I really enjoyed that one!
I loved all of Raph's lines about Karai like, "I don't trust her.", where he was going to stick his sai

, "I told you!", and "Some of us choose to be right all the time." Some of them reminded me of myself and how I like Nick's take on Raph a lot.
Mikey was smart in this one!!! I really liked that. He knew about triangulating the T-phones and when he suggested he knew where to go towards the end of the episode, Donnie's reaction was just priceless; "I feel scared."

I laughed out loud so hard on that one!
I really liked Karai's story too. I liked that she was still betraying them all the way until she saw the pictures of her and her real parents. I liked that it took that long for her to believe Splinter and Leo about her true father. The end with Shredder surprisingly admitting that "Yes, Hamato Yoshi
is your true father." was pretty interesting I thought. Shredder could have still tried to lie I thought but he told her the truth and it won't help her in the future either. All together a really great episode.