When SpongeBob unintentionally remembers how to make a krabby patty before Mr. Krabs, the order of the ingredients was switched around. For example, when making one at the beginning, the ketchup and mustard were added immediately following the patty, but when he remembers, the ketchup and mustard were near the top.
When Spongebob and Patrick pull out donuts to "unite", Patrick is clearly seen to pickup a donut, leaving the chocolate one in the box. When they "unite" he is shown having a half eaten chocolate donut. The switch continues to repeats throughout the show.
Spongebob is making his own Mermaidman movie, it is said that Patrick kept the lens cap on during the entire film, but, you can easily see that that is not true, since you see the camera filming without a lens cap.
When SpongeBob and Patrick paint Mermaid Man and Barnacle Boy's invisible boatmobile (thus making it visible), Mermaid Man is amused, but Barnacle Boy is not, stating that "It's supposed to be invisible!" However, in "Mermaid Man and Barnacle Boy II", Barnacle Boy tells Mermaid Man that "making the boatmobile invisible was a stupid idea", so Mermaid Man should've been the one to react.