The Turtles discover they have been sent back to the moment in time when the split between Oroku Saki and Hamato Yoshi came to a head and find their entire future at stake.
- A Pupil of Mine Until He Turned to Evil: The entirety of the Hamato Clan defect to Saki's new Foot Clan.
- Battle Amongst the Flames: Saki and Yoshi's final clash takes place like this, as the show's flashbacks have shown.
- Bittersweet Ending: The Turtles return home safely and the timeline has been restored, but they now live with the knowledge that they couldn't change Splinter's life for the better- not to mention having witnessed the horrific falling out of Saki and Yoshi. However, it was all meant to happen and the Turtles weren't supposed to do anything about it except save their master's life.
- Bloodless Carnage: Tang Shen is not shown to be bleeding from the fatal slash from Shredder.
- Continuity Porn:
- The entire backstory of Yoshi, Saki, and Shen that has been related to us in pieces over the years is finally shown in full in this episode.
- Donnie mentions that if Shen chooses Saki, then among other things, the Turtles will never save New York from the Kraang invasion, which took place in "Battle for New York".
- Yoshi and Saki's training hearkens back to the sparring session that opened the series. Their poses also resemble the ones they will later assume when fighting in the first season finale.
- Darker and Edgier: This is easily one of the darkest and most drama-heavy episodes of the entire series.
- Diegetic Soundtrack Usage: Mikey hums the show's theme when doing a little jig for Tang Shen.
- Dramatic Irony:
- Yoshi was torn between his loyalty to lead the Hamato Clan with his father bedridden and his wife and newborn child, who represent a new future abroad, a struggle that weighs on him heavily. However, the rest of the ninjas that make up the Hamato clan betray Yoshi and his father, defecting to Oroku Saki and becoming the new Foot Clan, their once-sworn enemies. While Yoshi and Saki have their duel, the turtles have to fight the traitors.
- Tang Shen was worried that staying with Yoshi would mean marriage to a man obsessed with his ninja clan, who would mold their innocent daughter to become a violent ninja. Ironically enough, Saki ultimately becomes that man, if in different configurations: obsessed with revenge, and brainwashing Miwa into the vindictive snake monster Karai.
- Building on the above, Tang Shen told Yoshi he could either be a ninja or a devoted family man, but never both. As the audience has witnessed throughout the series, Yoshi (as Splinter) managed to have his cake and eat it too: he managed to raise the turtles as their surrogate father and train them diligently as their sensei. If anything, he only trained them as a necessity, as opposed to Shredder who made it Karai's entire lifestyle.
- Et Tu, Brute?: Yoshi, when Saki attacks him with intent to kill.
- Even Evil Has Loved Ones: Shredder proves once and for all that he really has loved Karai when he gently takes Miwa as his own, believing Yoshi to have died alongside Tang Shen.
- Foregone Conclusion: The Turtles don't realize until the end that Shen was always destined to die at the hands of Saki.
- Green-Eyed Monster: Saki, whose jealousy of Tang Shen's love for Yoshi is seen in full in this episode.
- Face–Heel Turn: The Hamato Clan ninjas, when Saki convinces them to join him.
- Kappa: When Tang Shen meets the Turtles, she presumes that they are Kappa. While every other person who sees them are scared to death of them, Tang Shen invites them into her home and feeds them cucumbers (an alleged favorite among the turtle youkai), even trusting Leo to hold baby Miwa.
- Kid from the Future: The Turtles avoid Yoshi, but actually sit down and have a talk with Tang Shen and play with baby Karai/Miwa, their adoptive mother and sister respectively.
- Large Ham: The Turtles get a little too into their role pretending to be the soul-sucking yokai.
- Married to the Job: Yoshi is divided between taking over the Hamato Clan and ensuring its survival and going to start a new life with Tang Shen and Miwa. But the decision was made for him.
- Mook Horror Show: The fight with the Foot Ninja is shown from the Foot Ninja's perspective and the Turtles are presented as vastly more horrifying than normal, crawling on all fours on various surfaces while laughing and making jokes as they take down the ninjas one by one.
- Mythology Gag:
- The Turtles have been mistaken for kappa in numerous past Turtle stories. The myth of the yokai also played a role in the tie-in material to the recent 2014 film.
- The Turtles indirectly led Saki to reform the Foot Clan, much like in the original Mirage comics where the time-traveling Turtles indirectly led to the creation of the Foot.
- No-One Could Have Survived That: Saki believes Yoshi perished in the burning Hamato Clan's dojo. In a lesser example of this trope, Donnie mentions that they saved New York from the Kraang, affirming that the Turtles believe that their clash with the Kraang in "Battle for New York" was their last (when promotional material for the fourth season has already proved otherwise).
- Origins Episode: For not only Splinter and Shredder, but for the Turtles themselves.
- Retcon: The flashbacks detailing Saki taking Miwa made it appear that he knew Yoshi was alive and took Miwa with clearly malevolent intentions (even though "Rise of the Turtles" has Shredder surprised that Yoshi is alive). This episode sets the record straight for good by revealing that Saki believed Yoshi was dead and genuinely took Miwa to raise as his own. Additionally, see Unreliable Narrator.
- Not necessarily, as the episode's narrative cuts off (with Saki finding baby Miwa) right before Yoshi's previous flashbacks pick up (with Yoshi emerging from the burning building and seeing Saki walk away with his back turned)
- Retirony: Played with. After talking it out with his wife, Yoshi planned to leave his ninja ways behind for the sake of Tang Shen and Miwa. Unfortunately, by the time he comes to this conclusion, it's already too late, as Saki's arrival sets the events into motion. While Yoshi ultimately survives the outcome, there's a certain cruel irony that his decision to leave his old life came too little too late.
- Say My Name: Upon regaining consciousness and holding their flower, Yoshi can only agonizingly scream Shen's name in despair.
- Shout-Out: When Donnie notices that Casey is fading from the group shot photo on his T-Phone due to history changing, Mikey remarks that "It's just like that movie!"
- Spanner in the Works: The Turtles believe themselves to be this at first, until...
- Stable Time Loop: It is revealed that it was the Turtles' appearance to the Hamato Clan that pushed Yoshi and Saki to their violent history, and that the Turtles were always destined to be the ones who saved Splinter from Shredder.
- Set Right What Once Went Wrong: The Turtles decide to kill Shredder when their timeline begins fading out of existence, but ultimately their actions in the past were always destined to happen.
- Taking the Bullet: Tang Shen throws herself between Saki and Yoshi and dies for it.
- Technicolor Ninja: The Hamato Clan Ninjas running around wearing bright red in a woodland setting is a pretty egregious example of this.
- Trademark Favorite Food: Believing them to be Kappa, Tang Shen offers the Turtles cucumbers. Mikey is quick to inform her that their favorite food is actually pizza, but he eats the cucumbers anyway and develops a taste for them.
- Tragic Time Traveler: The turtles are hurled sixteen years into the past, when Hamato Yoshi and Oroku Saki were still friends and Tang Shen was still alive. To make sure that the timeline goes the way it's supposed to after their interactions with the Hamato Clan threaten their future, they discover that they were partly and indirectly responsible for causing the violent feud between Splinter and Shredder. The tragedy is worsened as they had to do it in order to ensure their own birth by rescuing Yoshi so he would go to New York, become Splinter and raise the turtles. The turtles are less than pleased with this revelation to say the least.
- Unreliable Narrator: It's revealed that Splinter was not entirely telling the truth during his flashbacks to his life before Tang Shen's death. Saki was not entirely motivated by jealousy when it came to Shen, as Yoshi was genuinely stumped on whether he should choose his family over his ninja clan, whereas Saki was willing to even take on a child that wasn't his own to provide a better future for her and Shen. Furthermore, Saki has plenty of reason to be enraged about the extinction of the Foot Clan at the hands of the Hamato Clan, so the conflict wasn't as black and white as Splinter has told it. Splinter probably wasn't telling his sons everything out of self-delusion, but this episode certainly casts the war between the Hamato and Foot clans in a new light.
- Depends on the viewer's interpretation, as Yoshi's dilemma was more over whether to raise Miwa in the Hamato Clan (as he wanted) or abroad (as Shen wanted), not whether to choose family or the clan. And Saki was still trying to break up Yoshi and Shen's relationship after they had married and had a 1-year-old child.
- What Happened to the Mouse?: We don't see what happens to Yoshi and Saki's master, but he was clearly not long for this world as it is. And the Hamato Clan has all but dissolved.
- You Can't Fight Fate: The Turtles try to save Tang Shen and prevent her from leaving Yoshi for Saki, but wind up inadvertently ensuring her death at the latter's hands and giving birth to their sworn enemy, the Shredder.
- Your Soul Is Mine!: Saki's ninjas are convinced the the "Yokai" are going to steal their souls.Leo: That's right, ninja. We yokai will steal all of your souls! Though your butt! Mwahahaha!Raph: Through your butt?!
