A minor one occurs between Leo and Mikey's cat, Klunk. In "Dragons Rising" Klunk approaches Leo in a friendly manner, but Leo is spiraling into Knight Templar-hood, and abruptly ignores him. In this episode, when Leo finds a sleeping Mikey, Klunk initially spits and snarls at Leo. Now that He's Back to his old self, the turtle's face softens and he strokes Klunk gently, at which point the cat realizes who he is and purrs appreciatively.
Leo references the events of "City at War, Part 3", when he fought alongside Karai, and told her she was nothing like the Shredder because she understood honor.
Curb-Stomp Battle: Leo effortlessly defeats Karai due to him being focused and her being consumed with revenge.
Good Colors, Evil Colors: A very subtle one occurs with Karai. Normally she wears pink lipstick, but for this episode she wears red lipstick, symbolizing her crossover into evil when she believed she's killed the Turtles. After Leo defeats her the next time we see her she's gone back to the pink lipstick, showing she's not so evil and such a threat anymore.
He's Back: When Splinter looks into Leo's eyes he can tell that his son is his old self once again.
"I remember when we first met, Karai. We fought side-by-side, and I said you were nothing like your father. I thought you understood honor, but I was wrong. You're exactly like him. You understand nothing!"
Trail Of Breadcrumbs: Leo tracks down his family by following their footprints, the wreckage of their vehicles and the items they leave in their wake.
Worthy Opponent: Karai is rather impressed that Leo was able to infiltrate her headquarters.
"Security is very tight and yet here you are undetected."