As seen on Nickelodeon's Random! Cartoons.
Pen (named Finn in the series) and Jake are hanging out in a field. A creature, who Jake identifies as "Princess Bubblegum's pet rainicorn", flies by while crying. Pen tries to cheer her up by telling her a knock-knock joke. The rainicorn keeps sobbing and flies on. She heads into the Ice Kingdom and begins to engage the Ice King in battle. Pen, peering after her with a pair of binoculars, sees Princess Bubblegum imprisoned in Ice King's lair. He and Jake enter the Ice Kingdom, making their way past various creatures. Pen starts fighting the Ice King while Jake chats up the rainicorn. Ice King lands a direct hit on Pen, encasing him in ice. Pen's mind is transported back in time and to Mars, where he meets Abraham Lincoln and is told to believe in himself.
He returns to the present and breaks out of the ice, in time to see Ice King fleeing with Princess Bubblegum thrown over his shoulder. Pen jumps on Jake's back and they and the rainicorn chase after the Ice King. Pen jumps and snatches the princess away from the Ice King's grasp, and the two of them are caught by the rainicorn as they fall. Jake defeats the Ice King by knocking off his crown, the source of his power, causing him to lose his flight abilities and plummet to the ground. Princess Bubblegum thanks Pen for saving her and kisses his forehead. Pen blushes and leaves with Jake. Jake teases Pen, but Pen changes the subject by pointing out some thieving ninjas, and the two friends run after them in pursuit of a new adventure.
Tropes:
- Ambiguous Situation It's specified that Pen goes back in time when he meets Abraham Lincoln, implying there's some reason he can't meet him in the present. He's perfectly fine in the main series, being 1000 years old up until he gives his immortality up to save Jake's life in "City of Mars."
- Big "NEVER!": When Pen breaks out of the ice block, he shouts "NEVER!".
- Crush Blush: Pen blushes when Princess Bubblegum kisses his forehead in thanks.
- Damsel in Distress: Princess Bubblegum has been kidnapped by the Ice King and needs to be rescued.
- Characterization Marches On:
- Ice King is a traditional cackling evil villain type here, a far cry from his rather pathetic personality.
- Princess Bubblegum is more of a straight Damsel in Distress here rather than the Science Hero she normally is.
- Early-Installment Weirdness:
- The main character is named "Pen" rather than Finn.
- Lady Rainicorn has no name, is referred to as Princess Bubblegum's pet, and speaks in pigeon noises rather than fluent Korean.
- The animation in general is much more primitive than the series proper. The backgrounds are little more than geometric shapes.
- Jake could connect to the internet with his mind for some reason.
- Gratuitous Ninja: The sudden appearance of the two ninjas at the end adds to the "random" feel of the story.
- Historical Hilarity: In an especially surreal sequence, Pen's mind gets transported back in time and to Mars, where he meets Abraham Lincoln.
- Leg Cling: On the title card, Jake is lying down at Pen's feet and clinging onto his leg in a parody of the trope. The series has them do the same in the opening sequence.
- No Name Given: The rainicorn is not named, at least in this pilot.
- No, You: When Ice King admits that he kidnaps princesses in the hopes of making one marry him:
- Rhetorical Question Blunder: After Pen throws snowballs at a fire elemental for no apparent reason, the elemental sarcastically asks how old he is. The implied dig at his maturity goes over his head.
- Savage Wolves: Pen is shown facing off against three huge, snarling wolves in the opening sequence.
- Smooch of Victory: Princess Bubblegum kisses Pen's forehead in thanks after he saves her from the Ice King.
- Spoof Aesop: Lincoln tells Pen to believe in himself. Pen then bursts out of his ice block with a cry of "NEVER!"
- Title Drop: When Pen and Jake are preparing to enter the Ice Kingdom.
- The Unintelligible: The rainicorn speaks in gibberish. (In the TV series, she speaks Korean instead.)
