MuscleBob BuffPants / Squidward, the Unfriendly Ghost - S1-E11
Plot hole: In MuscleBob BuffPants, when SpongeBob first shows off his new inflatable muscles to everyone on the beach, he had the strength to punch two muscular fish into the air with them. A minute later, he could not even lift a glass of juice with the inflatable muscles. (00:04:25 - 00:05:20)
Valentine's Day / The Paper - S1-E16
Plot hole: When SpongeBob goes to Sandy's house, he blows a chocolate bubble with the shape of a heart. Sandy opens a little door and the heart comes in. But, if the heart enters, don't you think that water would have also entered?
Answer: I believe this is the Season 6 episode "Spongicus".