Jimmy invents a small time machine. When he teases Cindy and Libby with his invention, Hugh asks to use it. When Hugh decides to go back 65 seconds, he types 6-5 , and sends Jimmy, Carl, and Sheen 65 million years in the past. Then Jimmy, Carl, and Sheen decide to make an invention to go back to their time. A T-Rex attacks, but they manage to hide under a giant mushroom, in the meantime Carl finds a Leptictidium, and names it Leppy. Suddenly, a pterodactyl, grabs Sheen and takes it back to it's nest and there are young pterodactyls.
Back in the present, Hugh uses Jimmy's invention to annoy the people of Retroville. He goes to the Candy Bar, and annoys them by eating ice cream for hours, and drinking purple flurp and burping all day. He signs up for parachute school, but annoys everybody by not using a parachute.
Back in prehistory, Jimmy and Carl and Leppy have finished up the invention and are ready to go home, but they need diamonds to power up the machine. Then Carl looks up in the sky and sees a huge star, and he asks Jimmy what it is, and Jimmy says that it's a huge asteroid coming down to Earth. Then Carl panics then Jimmy calms him down and says they've got 4 hours until the asteroid hits Earth.
Meanwhile, back at the nest, Sheen is having fun with the pterodactyls and the mother comes back and she since it is time to leave the nest, she pushes Sheen and the pterodactyls off the nest.
After a long time of searching, Jimmy, Carl and Leppy find a whole plethora of diamonds, but the T-Rex attacks, and it prepares to eat Carl and Leppy. Suddenly, Sheen appears and saves Carl and Leppy on the backs of the young pterodactyls. Jimmy remembers that the T-Rex's skull is harder than steel, so they use the T-Rex to crack the diamonds. But Jimmy notices that the asteroid has finally come to Earth. It crashes into the Earth and causes a big wall of fire spreading across the world to make the time of the dino's end and causing the T-Rex to run.
The time portal is set and Jimmy, Carl, Sheen and Leppy jump in the time portal, and they make it back to their time, but Hugh is captured and taken home by an angry mob of citizens.
Hugh is punished by being locked up in a cage. When Hugh is apologizing, Leppy pushes a random button on the remote and Jimmy goes back to the time of the beginning of the first part of the episode and Jimmy ends the episode surprised, saying to himself: "Whoa. Deja-vu."
- The title of this episode is like the Jurassic Park logo.
- Starting with this episode, Libby now wears a pink long sleeved shirt, brown shoes and blue flared trousers.
- This is the Quantum Replay's only appearance in the show.
- Jimmy said they went back two hundred million years to the Late Cretaceous period; said period was actually 65 million years ago (200 million years ago is the Triassic period).
- When the Pterosaurs were on the ground they should have their fingers on their wings on the ground to support their weight.
- It is true that the Leptictidium has been alive since the late cretaceous period.
- If Leppy rewound the whole episode, the events of this episode probably didn't happen, because Leppy would have rewinded it again and again and again and the rest of these episodes after this one couldn't exist, or Jimmy could have changed the timeline resulting the events of just this episode never happening.