Thanks to a thunderstorm, Peter Potamus and So-So arrive in the land of the giants, where they encounter a giant who is waiting for Jack to arrive to capture him.
Peter Potamus is captured by Romans and forced to fight with the lions in the Coliseum.
In Ancient Egypt, Peter Potamus agrees to help Caesar conquer the heart of Cleopatra.
Peter Potamus and So-So are hired by the king to stop the fire-breathing dragon that has been terrorizing the town.
Peter Potamus and So-So fly over a caravan of wagons that are headed for Hollywood but first they must get past the Indians.
Peter Potamus lands on Captain Kidd's ship, the Bounty, just as his crew deserts him. The Captain recruits Peter as his new crew, against Peter's wishes.
Peter Potamus lands in Sherwood Forest and meets Robin Hood.
Peter Potamus and So-So land on Mars and a movie director asks Peter to star in his new movie.
Peter Potamus gets locked inside a haunted mansion and gets chased by a ghost.
Peter Potamus is mistaken for an island god known as Omega by the native island people and must pass a few tests to prove himself.
Peter Potamus lands in between an ongoing feud between Zeke Quagmire and Maudie Scrag.
Peter Potamus meets Little Red Riding Hood and tries to protect her from the wolf.
Peter Potamus and So-So find an uninhabited island and find a pirate trying to bury his treasure.
Peter Potamus and So-So end up in the days of King Arthur.
Peter tries out a new time-space machine and ends up in old west Arizona. Peter jumps out of the balloon and lands on and disables the village's avenger, Senor El Zingo. Peter takes the place of the avenger to face the villain Don Jose el Tic-tac-taco. The villain is done in by Peter's hippo hurricane holler. Peter sends El Zingo, with nothing to do now, to Don Jose as well.
So-So spins the time-space machine and sends the balloon to prehistoric times. Peter removes a thorn from a dinosaur's foot. Now they can't rid themselves of the grateful dinosaur but are elated when the dinosaur saves Peter from an attacking caveman. The dinosaur, imitating Peter's hippo hurricane holler, accidentally sucks the balloon inside his belly. Peter and So-So, on the balloon still inside the dinosaur, float off.
Peter and So-So escape an attacking fish using the time-space machine. They end up under fire by World War I ace, Baron von Rip-em-up. The troops on the ground think Peter was sent by headquarters to fight the Baron. The two dogfight in biplanes. The Baron's apparent advantage in the battle is lost when Peter uses his hippo hurricane holler.
Peter gets out of a bad storm using the time-space machine and ends up in Verona, Italy. He falls out of the balloon and disables Romeo. Romeo enlists Peter's help to go get Juliet but Juliet's father is trying to prevent it. Juliet's father is sent away with Peter's hippo hurricane holler. Romeo and Juliet are married and go off on their honeymoon together using Peter's balloon.
The time-space machine takes Peter and So-So to the old West. Peter lands in a train and is sworn in as a marshal before the real marshal jumps off the train. Peter battles Jessie Jimmy, who is trying to rob the train. Jessie is finally defeated with Peter's hippo hurricane holler, which blows Jessie right to the State Prison.
Merlin, the magician, is enlisted by King Arthur to find someone to battle an ogre. The time-space machine takes Peter and So-So to Merlin at that time. Peter reluctantly fights the fire-breathing ogre and defeats him using his hippo hurricane holler.
Caught in the middle of a hillbilly feud, Peter and So-So escape using the time-space machine. It takes them to a village being attacked by a monster made by mad scientist Plankenstein. Peter defeats the monster with his hippo hurricane holler. Plankenstein uses the monster parts to build a merry-go-round for the villagers.
Peter is forced by villagers to get their tax money back from a tyrant. It looks like he will fail until he resorts to using his hippo hurricane holler, which blows the money back to the villagers. The tyrant then announces higher taxes because of the depletion of his treasury and now the villagers are mad at Peter, who escapes in the balloon.
Using the time-space machine, Peter and So-So escape from attacking island natives, a caveman, a WWI flying ace, and a British man-of-war ship before finally landing in the old West. Peter looks just like a bandit on a wanted poster. He's arrested by the sheriff but escapes using his hippo hurricane holler.
Peter and So-So meet Christopher Columbus, who appoints Peter as his emissary to some hostile Indians. Peter fails with negotiations until he resorts to his hippo hurricane holler. The Indian chief capitulates and signs the peace treaty. Columbus gives Peter the title Don Peter Potamus.
Peter and So-So land in America during the time of the Revolution. Peter and So-So spread the word that the redcoats are coming from their balloon. They are shot down by British soldiers. They escape pursuit donning British uniforms but then are chased back to their balloon by American troops.
Peter and So-So end up in Colonial America, where they meet Miles Standoffish. He wants to marry Priscilla, but she refuses to become his wife unless he can prove he's a good provider. Peter helps him by using the Hippo Hurricane Holler to round up wild game. Priscilla agrees to marry Miles, but in the end, it turns out all she wanted was for him to do all the housework while she nagged him to death.
Peter and So-So evade a missile using the time-space machine and end up meeting William Tell. Because William fails to remove his hat in front of the king, he is given the punishment to shoot an apple off his son's head. Since it was Peter's fault, William makes Peter take his place and shoot an apple off So-So's head. Peter misses and is pursued by both the king and William. His hippo hurricane holler causes an avalanche, which enables them to escape.