
Revealing mistake: At the end of "Wormy", Patrick's eyes are missing.

The Secret Box / Band Geeks - S2-E14
Continuity mistake: When SpongeBob is sneaking to Patrick's house, Squidwards house is missing.

Dying For Pie / Imitation Krabs - S2-E6
Revealing mistake: In the episode "Dying For Pie", you can see Mr. Krabs' legs disappear when Squidward says, "But you can't pay me enough to act brotherly on that guy!"

Your Shoe's Untied / Squid's Day Off - S2-E2
Character mistake: In "Squid's Day Off", a wide shot shows Mr. Krabs exiting the hospital, except the building says" ENEREENCY" instead of "EMERGENCY."

The Secret Box / Band Geeks - S2-E14
Continuity mistake: In Band Geeks during the Day Two scene, in the beginning you can see Pearl near the front, but in the distant shot that follows Pearl has moved further back. (00:04:20)

Big Pink Loser / Bubble Buddy - S2-E3
Revealing mistake: Big Pink Loser: When Patrick says, "Why can't I do anything right?", and starts hitting his broom on the floor, the drinks that are supposed to be on the customers' tables are instead layered behind them. (00:05:18)

Big Pink Loser / Bubble Buddy - S2-E3
Revealing mistake: Big Pink Loser: When Patrick is answering phone calls, the third time he picks up and says, "No, this is Patrick", the anchor symbol on his hat briefly vanishes. (00:04:36)
Suggested correction: This mistake can only be detected by freezing the film and advancing frame by frame. It is not visible while watching the film at a normal running speed. According to the rules of this site, this invalidates the error.
So, I reworded the mistake to say that it "briefly vanishes," because it's actually gone for a few frames, not one. I did not advance frame by frame to find the error. If you watch the scene at normal speed, it disappears for a brief moment, then comes back. I assume this correction might have been made without watching the scene, especially since the show was referred to as a "film."
This is not true. You can see it disappear if you watch it at normal speed; it does not require pausing at all. At least, I am able to see it.

The Secret Box / Band Geeks - S2-E14
Continuity mistake: When the band is marching through the streets, whilst Squidward is pressuring the flag twirlers to move faster, there are some fish drumming behind them. One is a blue fish wearing a yellow shirt seen standing on the left, and another is a brown fish wearing a red shirt seen standing on the right. When the flag twirlers behind to fly off the ground, those two fish have swapped places.