Continuity mistake: In the episode "The Bully," when Flats punches Spongebob, Spongebob states to Gary that he's made out of some spongy material, that it absorbs his blows and it doesn't hurt him at all. But in later episodes, when Spongebob gets knocked out that never happens anymore.
Character mistake: In the beginning of "One Krabs Trash" Spongebob only has one bill in his hand, a 5 dollar bill. When he goes to his house and comes back, he says he found 68 cents. Therefore, he has 5 dollars and 68 cents. However, he has two dollar bills and a few pennies in his hand, which cannot be made into $5.68.
Continuity mistake: When Patrick is dressed as food for the "monster" in "Wormy," when the butterfly is on P,atrick's butt he spits out the apple in his mouth and it floats to the top of the water helmet. But when the butterfly is on his helmet, the apple is gone.
Continuity mistake: When Gary and Spongebob are waiting at the door, there is a sign behind him that says "pin the tail on the horace" (yes it says horace), and there is one tail hanging up, but when everybody comes in there are suddenly two.
Continuity mistake: During Spongebob's act, he says to the audience, ".I'd like to give a special thanks to my friend Sandy over here" and the spotlight moves from Spongebob to Sandy. A few shots later, when Spongebob is talking to Sandy, the spotlight is suddenly no longer on Sandy. Then when Spongebob yells "Am I right?" to the audience, the spotlight is on him and as he turns to talk to Sandy again, the spotlight is altogether gone; it's not on either one of them.
Continuity mistake: When Squidward starts making pink bubbles with messages, he goes to his backyard. Notice he never closed the back window of his house. When he starts laughing because of the messages, suddenly the window is closed. After Patrick saves Squidward, the window is still closed, but when they go to the front of his house, the window is open.
Continuity mistake: When Spongebob shows Patrick the good noodles chart all the stars are wildly scattered in each row. When Patrick is trying to announce his name to the class they're all in a neat row. When Mrs. Puff is removing the star from Spongebob's row they're scattered again.