Original air date: 5/4/2001

Production code: PPG-403

When Professor Utonium invents a time portal for a demonstration during career day at the Girls' kindergarten, Mojo Jojo uses it to travel back in time and try to kill the Professor when he's still a child.

Get Back Jojo provides examples of:

• The '50s: Professor Utonium's (along with Ms. Bellum and Ms. Keane's) school day takes place in 1959.
• Acid-Trip Dimension: The fifth dimension through which one must go to achieve time travel.
• Art Shift: Mojo's trip through the fifth dimension is rendered in pencil sketches.
• Bait-and-Switch: We're introduced to who we thought is a younger version of Utonium, but he's just a random nerd being picked on by the real Utonium. Downplayed since the Professor already foreshadowed it.
• Big Damn Heroes: The girls save the young Utonium just before he hit the smoldering lava, and he notices them which resulted in the Stable Time Loop where he became interested in science.
• Big "NO!": Mojo Jojo during the end sequence, when the narrator points out that he once again had a hand in creating the Powerpuff Girls. The narrator counters with a Big "YES!".
• Butterfly of Doom: Discussed; the Professor warns the girls to be very careful while in the past, and not use their powers unless forced to, since anything they do could potentially change the timeline.
• Call-Back: When Mojo kidnaps the young Professor Utonium, Utonium having none of Mojo's scheming calls him Daddy-O, a catchphrase he used once when he faced Mojo as PowerProf.
• The Cameo: Gerald McBoing-Boing and his parents appear in the movie shown at the classroom in 1959.
• Climbing Climax: Mojo climbing the volcano with the young Utonium as his captive. He has to climb since in 1959 his observatory, and the staircase leading to it, have not been built yet.
• Continuity Nod: At the end of the episode, the narrator announces (much to Mojo's chagrin) that the day was saved thanks to him "once again" accidentally did his part in the creation of The Powerpuff Girls.
• Create Your Own Hero: For the second time, Mojo Jojo is somehow responsible for the girls' creation. The narrator even lampshades it.
• Didn't Think This Through: Although never brought up in the episode, Mojo overlooks the small, yet critical fact that the same lab accident that created the Girls is also how he came to be sapient, therefore he would have undone his intelligence as well.
• Even Evil Has Standards: You know you're a bad boy when not even the #1 villain in Townsville approves of your bratty behavior.
• Everyone Went to School Together: Utonium was in the same elementary school class as Ms. Bellum and Ms. Keane.
• Foreshadowing:
  • The Professor tells us that there was a time when he wasn't interested in science. This comes into play when we see that the young child Utonium was not interested in school, much less science.
  • Mojo and the Powerpuff Girls journey to the past all being part of a Stable Time Loop is foreshadowed by an earlier demonstration when the Professor pulls out his own keys from the previous day through the portal and realizes that's why they went missing.
  • There's a major indicator that the Young Professor had a gift for coming up with crazy science experiments even before he becomes interesting in Science. During Chemistry class, he's shown making a monster out of the clay intended to make a volcano science project and fiddling about with chemical that caused an explosion, much like how he creates the Powerpuff Girls. Seeing the girls was the catalyst that channeled his creativity into a more productive means.
• Hero Insurance: The damages caused by Townsville's frequent monster and supervillain attacks is given a nod when one of the parents reveals his occupation involves insuring buildings against damage, and that he's a very busy man.
• Hyperspace Is a Scary Place: When Mojo uses the time portal to travel back, the professor states that transporting a complete person is a lot harder than small objects, and Mojo may not even survive his trip through the Fifth Dimension. Mojo survives alright, but you can tell from his reaction that the time travel is very unpleasant. Bubbles has a similar reaction.
• Impairment Shot: After saving the young Utonium, the girls are seen blurred against the sun from his hazy perspective, which is what inspires him to become a scientist and create "the perfect little girls" years later. Later when the Professor frees the girls and Mojo from the time portal near the end, a similar shot of them blurred and hazy against the ceiling lights is shown from his perspective after they plow into him.
• Instructional Film: Utoniums' class in 1959 is shown one about the dangers of the Townsville volcano.
• Jerkass Has a Point: Mojo Jojo was right about the Professor being a brat as a child. He was also right to call him foolish for carelessly mixing different chemicals.
• Just in Time: The girls forget walking and quickly take to the skies, saving the young Professor just in time before he hit the lava.
• Mistaken for Flatulence: A younger version of the Professor tricks his classmate Matthew into sitting on a Whoopee Cushion, which makes a flatulent sound. Their teacher thinks Matthew broke wind and makes him sit in time-out.
• Mugged for Disguise: Mojo Jojo does this to Mary from "Ice Sore" and "Mojo Jonesin'" to get into the school unnoticed.
• Oh, Crap!: The girls get a shared one when they see Mojo Jojo throw the young Professor into the volcano.
• Older Than They Look: Professor Utonium, Ms. Keane, and Ms. Bellum all went to school together in 1959 as young kids (likely out of Kindergarten) and likely be in their forties at the least at the date the episode aired (2001) but they don't resemble middle-aged adults (especially Ms. Keane). What's more, the Mayor in those days is still the Mayor of today, just with more hair (which was still white even back then).
• Paper-Thin Disguise: Mojo's disguise as Mary. Still, everyone falls for it until he reveals himself.
• Portal to the Past: The professor's time portal.
• Recycled Soundtrack: The music played when Professor Utonium reveals the girls who saved them in his childhood were the Powerpuff Girls themself travelling back in time, is the same cue taken from "The Rowdyruff Boys" when the girls kiss the boys to defeat them.
• Red Herring: When Mojo first arrives in the past, he spots an intelligent young boy who looks like a younger Professor Utonium and even has the same voice, just younger sounding. Then he's yanked off his stool by the real younger Utonium.
• Reformed Bully: Surprisingly, Professor Utonium is revealed to be one of these. He was quite a Bratty Half-Pint during his youth who liked to pick on the nerd in his class. Good thing that he redeemed himself after discovering science, and became the good man we all know him to be.
• Save the Villain: The girls save Mojo from falling into the volcano, since they decide they can't leave him behind in the past.
• Set Wrong What Was Once Made Right: Mojo attempts to go back in time and prevent the girls from ever being created so he can rule unchallenged. The girls have to follow him to the past and save the Professor.
• Shoo Out the Clowns: The narrator is completely absent throughout the entire episode until the end shot, to make the time traveling experience more serious.
• Stable Time Loop: Mojo goes back in time to kill the young Professor Utonium. Instead, his actions and those of the girls are what inspire Utonium to become a scientist and one day create the girls. On a smaller note; when testing the time portal, the professor retrieves his car keys from the day before. He even states "so that's where they went".
• Sudden Soundtrack Stop: When Ms. Keane interupts the moment between the Professor and the girls after they return to the present, the background music stops as well.
• Time and Relative Dimensions in Space: The time portal allows for both a time and a geographical location to be programmed, so it can send you anywhere and anywhen.
• Time Travel Episode: The main plot of this episode.
• Tragic Time Traveler: Mojo Jojo uses a time portal created by Professor Utonium to go back in time in order to prevent the professor from creating the Powerpuff Girls by killing him. However, doing this causes the girls to fly back to stop him, and this causes the younger professor to decide to become a scientist one day, rendering Jojo's travel for naught.
• Word, Schmord!: When the girls see Mojo throw the young Professor into the volcano, Blossom cries, "Walking, schmalking! Let's fly!" just before they save him.
• Wrong Time-Travel Savvy: Mojo goes to the past thinking he'll be able to alter history by preventing the young Utonium from getting the idea to create the Powerpuff Girls. Too bad for him that time travel works by Stable Time Loop rules in this universe.