Before Gumby leaves for his next gig, he tells Denali to squirt some super-growth formula on his watermelons. His chore done, Denali goes to sleep, giving the Blockheads free access to Gumby's melons. They make off with half of the crop before Gumby's livestock notices. The Blockheads sell the watermelons in town, but the formula makes them grow huge, have eyes, and run around smashing things. Denali redeems himself by popping the fruits like balloons with chunks of ice, ending their reign of terror. The newspaper tells the story of the melon thieves and the heroic mastodon, discretely forgetting to mention that it was Gumby's stupid fault that they got all mutated to begin with. I bet he greased a few palms.
It's little sister Minga's birthday, and that means a full day at Pumpkin Land Amusement Park, the pumpkinest place on Earth. There's a plethora of pumpkin-based foods, such as Pokey's much-desired Pumpkin Puff; pumpkin-themed rides like the Pumpkin Train and the Pumpkin Ferris Wheel; and, of course, attendants with evil Jack O'Lantern heads. Hooray! The action revolves around the Blockheads, who've jumped the fence and broken into the park. After a merry chase, the Blockheads are flattened by a giant pumpkin, and Pokey eats so many Pumpkin Puffs that he turns into a pumpkin himself.
Professor Kapp has invented a really real time machine, and, together with Gumby, Pokey, and Denali, he goes for a merry trip to Egypt, 2001 B.C., where he and Gumby are instantly enslaved. They telephone Prickle, who's still in the present, and have him bring them back, but he has some sort of problem with figuring out a simple keypad, so he keeps sending them to the wrong year. The traveling clay figures visit roughly a half-dozen popular historical events, completely screwing up the time line, before Prickle figures it out and brings them back to 1988.