Revealing mistake: In "The Algae's Always Greener", Squidward walks in to the office to complain about SpongeBob's new rank. But when Squidward walks in, the krabby patties from the scene before are missing. Then after SpongeBob talks after Squidward complains, the krabby patties are back.
Continuity mistake: Plankton! When SpongeBob and Plankton are talking at night Plankton gives SpongeBob a golden spatula. When Plankton says he wants a Krabby Patty for his birthday SpongeBob drops it. Then when SpongeBob walks away, the spatula is nowhere to be seen.
Continuity mistake: When Mr. Krabs comes upon an elderly person, the old man tells him to wait in line like everybody else, and then Mr. Krabs sees a bunch of elderly people waiting in line in front of a cemetery. Seconds later a man handing out ice cream to the elderly people suddenly appears in front of the entrance.
Continuity mistake: Throughout the whole episode of "Missing Identity", SpongeBob's shirt is backwards. This is seen with his sleeves being supposedly behind him. The sleeves are missing from the front, which is normal, but throughout the episode, pay attention to behind SpongeBob. His sleeves are supposed to be behind him, but are missing altogether.