When Spongebob finds an old Patty under the grill Mr. Krabs tells him that he won't be allowed to make another Krabby Patty until the old one is sold, but afterward when the old one is being sold, you can see that there are other customers eating, which means that Spongebob made other Krabby Patties before cooking the old one.
When the Flying Dutchman takes the change out of his pocket, it appears as both silver and copper coins in close-up, but in later shots the coins are all copper.
When Squidward wakes up from his nap, he enters from the right of the order counter. Mr. Krabs' office, where Squidward moved his bed, is on the left.
The doctor says SpongeBob's butt was repaired with glue due to running out of staples, but the x-ray shows the butt pieces being held together with tape.
When SpongeBob gets ripped in half and says "It's too late," the close-up of the gorilla's face uses the same exact background as SpongeBob's left half.