Procrastination / I'm With Stupid - S2-E19
Continuity mistake: In "Procrastination" when Spongebob is moving back and forth on his chair while writing his essay there is no pencil on the desk, but when he goes back to work on the essay there is.
Suggested correction: The pencil is sitting to the right of the paper the entire time. It's hard to notice at first, but it's there.
Tenacle-vision/I Heart Dancing - S7-E8
Character mistake: In "I Heart Dancing", the lady at the Krusty Krab tells Spongebob the dancing audition is the next day. Later, Spongebob is practicing at Squidward's house for a whole night, and the next morning Squidward says they have one more day to practice, even though the audition should have been that day.
Suggested correction: The audition could have been during the afternoon.
Jellyfish Hunters / The Fry Cook Games - S2-E16
Plot hole: As Spongebob is trying to let the Jellyfish out of their enclosure after discovering what Mr Krabs is doing to them, Krabs says, "That door will only open if I say...open." Then he suddenly realises what he's said and the door opens. How come the door didn't open when in his sentence he first said open? The door didn't activate itself until he said open the second time.
Suggested correction: Two likely explanations: 1. He said it more the 2nd time. 2. There was a delay.
Plot hole: In "Once Bitten", Mr. Krabs never unlocks the doors to the Krusty Krab, but at the end of the episode, Squidward enters with no problem.
The Snowball Effect / One Krabs Trash - S3-E3
Continuity mistake: In the scene where, Squidward accidentally squirts lemon juice in his eye it goes in his right eye but he squints with his left eye.
Suggested correction: In "The Snowball Effect", Squidward squirts the lemon wedge's juice into his left eye and he closes his left eye. There is no continuity error.
Other mistake: In "SpongeBob and the Clash of Triton," the title card says it is called "Neptune's Party," thus making it a wrong title.
Suggested correction: "Neptune's Party" was the original title for "The Clash of Triton."
SpongeBob Meets the Strangler / Pranks a Lot - S3-E20
Revealing mistake: In "Spongebob Meets The Strangler" when that fish holds up Spongebob's dry cleaning at the supermarket, it looks like he is holding it up with a coathanger because his hand is up in the air, but you can easily see nothing is holding it up. It's just floating up in the air.
Suggested correction: The clothes are being held up by a coat hanger. It may be hard to see due to it blending in with the wall color, but if you look closely, it's there.
No Free Rides / I'm Your Biggest Fanatic - S2-E10
Continuity mistake: When Spongebob writes an essay, at first he's in the middle seat on the front row, but after he gets his pen, he sits down at the desk to the very right.
Suggested correction: No, he is sitting in the middle the whole time.
Continuity mistake: If you look carefully, you will notice that on the title sequence, patchy the pirate's eyepatch changes eyes. This varies from episode to episode.
Suggested correction: The eyepatch doesn't change position from episode to episode. You must be thinking of "Christmas Who?" where Patchy accidentally hits himself in the eye with his hook. And the pirate from the theme song's name is Painty the Pirate. Patchy and Painty are two completely different characters.
SpongeBob Meets the Strangler / Pranks a Lot - S3-E20
Plot hole: In the end of "Pranks A Lot" SpongeBob and Patrick glue the door shut in order to keep Mr. Krabs inside the Krusty Krab. When SpongeBob And Patrick are visible again, it turns out that a lot of customers have entered the Krusty Krab to see SpongeBob and Patrick naked. All of those people had no way to get into the Krusty Krab with the doors glued shut. It can't be that they broke down the doors, as they're still there.
Suggested correction: Mr. Krabs most likely washed the glue off the doors and let the people in.
Help Wanted / Reef Blowers / Tea at the Treedome - S1-E2
Continuity mistake: In "Help Wanted" Gary doesn't have eyelashes. In every other episode he does.
Suggested correction: So Gary not having eyelashes could count as an early design for him. It's common that characters and environments may undergo changes after a pilot. Not a mistake.
But Gary never had eyelashes.
The Snowball Effect / One Krabs Trash - S3-E3
Continuity mistake: Throughout the episode "The Snowball Effect" Patrick's house is missing.
Suggested correction: I just watched this episode and on at least two occasions I could see Patrick's home in the background.
Help Wanted / Reef Blowers / Tea at the Treedome - S1-E2
Continuity mistake: The office door in the Krusty Krab is missing throughout the episode.
Suggested correction: It's a pilot episode. Things can change with a show when it gets picked up into a series.
Plot hole: After being spared, Medieval Sandy announced that she will help in the defeat of medieval Plankton. How did she know what they were planning?