New Student Starfish / Clams - S3-E14
Continuity mistake: New Student Starfish: Spongebob shows Patrick the Good Noodles board when they enter the classroom. Then when Patrick is trying to tell the class his name, the number of stars on it change, and the name "Rich" appears on it, which wasn't there before. Later on, when Spongebob and Patrick are in detention, the names on the board are completely different in some shots. (00:02:48 - 00:11:24)
New Student Starfish / Clams - S3-E14
Continuity mistake: In the episode New Student Starfish., SpongeBob's good noodle stars changes number throughout the episode.
New Student Starfish / Clams - S3-E14
Continuity mistake: When SpongeBob and Patrick arrive to the class, SpongeBob writes Patrick's name in the board. Notice that he writes it in capital letters: "PATRICK". After, when Patrick is asked to say his name to the class, and he becomes nervous, look at the board, at Patrick's name: now isn't in capital letters, is normal: "Patrick".
New Student Starfish / Clams - S3-E14
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.
Answer: I believe this is the Season 6 episode "Spongicus".