Serling is so sick of being stuck in the 21st century that he secretly builds a Time Window and uses it to return to 2105. Unfortunately his machine doesn't work properly, and instead shrinks him down to the size of a toy and sends him back to the time when the Turtles were little children.
This episode provides examples of
- Big Damn Heroes: Splinter shows up just in time to rescue his sons.
- Forgotten First Meeting: Due to time travel, the Turtles first meet Serling when they were toddlers. They don't recognize him later, partly because it was a long time ago and they forgot, and partly because he was so much smaller thanks to his Time Window's malfunction
- Percussive Maintenance: How Serling gets the Time Window to work in the first place
- Would Hurt a Child: The Turtle Tots meet an old man who unleashes an army of deadly toy robots and a life sized one to attack them.