In "The Magic Fountain", when Clumsy accidentally fell overboard near the end of the episode and was caught by Johan, he also has deep-sea drift-weed on him. However, it is actually seaweed.
One of the Feebles talks about their strength returning to them after drinking the water from the Magic Fountain, even though he said earlier to Johan and Peewit that due to an old curse, all of them are born feeble. Actually, due to the water they drank, they gain strength, not have it restored.