When inventor Baxter Stockman invents a rat-seeking robot called a Mouser, Shredder sees it as his key to eliminate Splinter once and for all.
- Conveniently Empty Building: It's hinted that April was the only one living in her apartment building when it was destroyed by the mousers.
- Cool Car: Sort of. Baxter just drives an ordinary van that would end up being used by the Turtles. In the next episode however, it becomes the iconic Party Wagon.
- Cut Lex Luthor a Check: We first see Stockman trying to sell his Mouser robot to an exterminator. He's thrown out because it might work too well, driving pest control out of business.
- Darker and Edgier: While Never Say "Die" was in effect, this episode threatens death and physical harm more than any other. We see a Mouser chomp a rat, Raphael physically threatens Stockman, Shredder orders some Foot Soldiers to put Stockman "out of the way," Splinter tells April he fears they will "join their ancestors" while fighting the Mousers, and April's apartment building collapses with Michelangelo inside (he's fine, of course).
- He Knows Too Much: Shredder says this word-for-word after having Stockman build him a Mouser master control, and sends his Foot Soldiers to do the dirty work.
- Nice Job Fixing It, Villain!: Krang helps the turtles ruin Shredder's mouser plan so Shredder can focus on building his new body.
- Oh, Crap!: The Turtles when they piece together how easily the Mousers can track people and there are now hundreds of them tracking Splinter and April.
- Out-of-Character Moment: In one scene, Raphael threatens to physically hurt Baxter if he doesn't tell the whereabouts of the Shredder.
- Title Drop: At one point, Baxter Stockman says "This Shredder must really have a thing about rats".
- What an Idiot!: In-Universe, Shredder calls the exterminator a "short-sighted fool" for missing an opportunity with Baxter's Mousers.note