SpongeBob SquarePants (1999)

SpongeBob Meets the Strangler / Pranks a Lot - S3-E20

Plot hole: In "Pranks A Lot", Patrick and SpongeBob scare Sandy. When Sandy runs, gets into her rocket and flies away. When she moved bubbles appeared meaning there's water in her tree house. There's no water in there in other episodes because she's a land animal and breathes air.

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.

SpongeBob Meets the Strangler / Pranks a Lot - S3-E20

Plot hole: When the invisible Spongebob and Patrick scare Sandy, they are using a sheet to appear as "ghosts". However, the form of the sheet reveals that they don't have their helmet bowls on. How could they survive in the treedome that time? They sounded fine, not dehydrated.

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.

The Secret Box / Band Geeks - S2-E14

Audio problem: At the end of "Band Geeks" when everyone is playing "Sweet Victory" at one point Mrs. Puff is shown playing the guitar. When this happens, you can see the others in the background not doing anything, even though their instruments are heard.

Jellyfishing / Plankton! - S1-E3

Continuity mistake: In Plankton! When Plankton pulls out a radio player to play his evil music on SpongeBobs pillow, it has disappeared when Spongebob wakes up. SpongeBob didn't move on it.

Not Normal/Gone - S6-E4

Revealing mistake: In "Not Normal" when SpongeBob says "Hmm. This video tape should help," his left arm is missing. (00:01:25)

Mermaid Man and Barnacle Boy IV / Doing Time - S3-E1

Plot hole: In "Mermaid man and Barnacle Boy", Plankton is shown as taller than the town at the end of the episode. However, when Spongebob is shrinking the people of Bikini Bottom, their sizes in the pickle jar seem to be equal with Plankton's actual height. In reality, Plankton should have been around the same size as the rest of Bikini Bottom's residence after the shrinking, not 5 times taller.

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.

Club SpongeBob / My Pretty Seahorse - S3-E12

Revealing mistake: In Club SpongeBob, when SpongeBob, Patrick and Squidward are in the forest, Squidward asks the magic conch shell if he can have something to eat. Straight after he asks "Can't you say anything else but 'No'?", it has a close-up of the shell. But Squidward's arm appears to be yellow, like SpongeBob's.

SpongeBob Meets the Strangler / Pranks a Lot - S3-E20

Continuity mistake: When The Strangler and Spongebob arrive at the pineapple, look at the door: there is no doormat below it, but a couple minutes later Spongebob pulls a key out from under the doormat that was not there before.

Something Smells / Bossy Boots - S2-E1

Continuity mistake: When Spongebob is playing the organ at night, he turns around and his glasses are on. In 2 of the 3 shots, the glasses disappear.

Have You Seen This Snail? - S4-E3

Continuity mistake: In "Where's Gary?" the length of the paddle ball string that SpongeBob uses seems to vary in certain shots. While the length is somewhat subjective one shot that is more conclusive is when Patrick finds Spongebob lying on the floor. The string on the paddle ball is fairly short. When the two get up to get a glass of milk, the string is now a lot longer.

Show generally

Continuity mistake: REAL 3-18: Plankton's Army (aka Plankton's Last Stand) / Missing Identity: When the screen splits into 4, the last 2 events are not in chronological order. That is, they are not in the same order as they always have been.

Jellyfishing / Plankton! - S1-E3

Continuity mistake: In Jellyfishing, when Patrick puts the net in Squidward's hand, at first it is in his left hand, but when he gets the jellyfish on the king jellyfish, it is on his right hand.

SpongeBob Meets the Strangler / Pranks a Lot - S3-E20

Continuity mistake: In "Pranks-A-Lot" when Sandy flies out of her dome in an escape pod to Texas, she leaves a big hole on top of her dome. In the next shot, it's gone. Very noticeable mistake.

Jellyfishing / Plankton! - S1-E3

Continuity mistake: Spongebob crashes through Squidward's house, and his bedroom is on the bottom floor. But in "Shanghied" after Squidward exits the fly of doom, you can see his bedroom is on the top floor, as it is in other episodes.

Show generally

Continuity mistake: The Krusty Krab kitchen sometimes has deep fryers, and sometimes it doesn't. When it does, the fryers change locations in the room between episodes.

Season 3 generally

Continuity mistake: In the episode "Missing Identity", when Spongebob is talking to Patrick about saying "hi" to him the first time, Squidward's house is gone.

Brad

Sleepy Time / Suds - S1-E15

Continuity mistake: When all of Spongebob's friends are formed around him, there's one scene where Pearl's hat disappears and then reappears, so for a few seconds she's completely bald. Her hair isn't even there.