Squidtastic Voyage/That's No Lady - S4-E15
Continuity mistake: In "That's No Lady", Patrick runs through Spongebob's wall, leaving a Patrick-shape in his house. Patrick pushes a bit of Spongebob's house, which disappears in the next shot.
Squidtastic Voyage/That's No Lady - S4-E15
Continuity mistake: In "That's No Lady", Spongebob has a tray with two lemonades and gives one to Patrick. In two shots, the tray and the two glasses of lemonade disappear.
Squidtastic Voyage/That's No Lady - S4-E15
Continuity mistake: In "Squidtastic Voyage", Squidward drinks many bottles of soda to try and get Spongebob and Patrick out of his stomach. Two shots later, these bottles all disappear without anyone touching them.
Squidtastic Voyage/That's No Lady - S4-E15
Continuity mistake: In 'Squidtastic Voyage", Spongebob uses a remote to open the doors of the submarine. This remote disappears in the next shot.
Squidtastic Voyage/That's No Lady - S4-E15
Continuity mistake: In "That's No Lady", Squidward is standing at the register, holding a newspaper. When it cuts to "Patricia", and back to Squidward, Squidward isn't holding the newspaper anymore.
The Thing/Hocus Pocus - S4-E16
Continuity mistake: The Thing: When Squidward is riding his bike on the road, he hits a cement truck, and gets covered in cement. He tries to get out of it, and a shot later, the location suddenly changes from the road to a green hill. (00:04:05)
The Thing/Hocus Pocus - S4-E16
Continuity mistake: At the start of "The Thing" the walkway to Patrick's house is missing.
The Thing/Hocus Pocus - S4-E16
Continuity mistake: In 'The Thing' the house of Squidward's door first opened outwards, then later inwards. It also changes color.
Driven to Tears/Rule of Dumb - S4-E17
Continuity mistake: In 'Rule of Dumb' Patrick's house returned to its former self in the outside shot just before Squidward's house was moved.
Born to Be Wild/Best Frenemies - S4-E18
Continuity mistake: When we first see Plankton, the distance between him and the Kelpshake store keeps changing between shots. (00:02:20)
Best Day Ever/The Gift of Gum - S4-E20
Revealing mistake: When Squidward says "I suppose if you haven't fixed my clarinet, the concert would have been a bust", Sandy's tail is the same color as her suit.
Best Day Ever/The Gift of Gum - S4-E20
Character mistake: SpongeBob tries to steal the gum off his door at night. The next day, SpongeBob says that it was still Best Friends Day, so he would give Patrick his gum back. Really, it should have been the next day.
Best Day Ever/The Gift of Gum - S4-E20
Continuity mistake: When SpongeBob tries to steal the gum at night, he's dressed as a bandit, but then the next day when Sandy finds him, he's wearing his normal clothing. He was stuck in the gum all night so there's no way he would have changed.
Rise and Shine / Waiting / Sing a Song of Patrick - S5-E1
Continuity mistake: In "Sing a Song of Patrick", Patrick creates his own song and listens to it with Spongebob in his pineapple. And at the end of the song the pineapple melts and the stereo falls on top of them and not the pineapple. But when they get up, the busted stereo disappears and the pineapple is on top of them.
Rise and Shine / Waiting / Sing a Song of Patrick - S5-E1
Factual error: As Patrick's song causes havoc, two airplane pilots deserts the airplane and deploy their parachutes. The issue with this is that the two pilots should have come to a stop relative to the airplane's movement.
Rise and Shine / Waiting / Sing a Song of Patrick - S5-E1
Continuity mistake: In "Waiting", SpongeBob has milk on his face. It then cuts, and the milk is not on his face anymore.
Spy Buddies / Boat Smarts / Good Ol' Whatshisname - S5-E4
Continuity mistake: At the beginning of Spy Buddies, when Mr. Krabs is entering the code to enter the Krusty Krab, it's night. But when Patrick yells about him wanting to be a spy and it shows the fish walking outside of the Krusty Krab, it is day.
Spy Buddies / Boat Smarts / Good Ol' Whatshisname - S5-E4
Continuity mistake: In "Good Ol' Whatshisname", Squidward is seen marking his calendar which has five weeks on it, and each row has a set of numbers. In the next shot, when it shows the rest of Squidward's jail cell, the bottom two rows of the calendar are completely blank.
Spy Buddies / Boat Smarts / Good Ol' Whatshisname - S5-E4
Continuity mistake: In "Good Ol' Whatshisname", Squidward uses a pencil to mark his calendar and sets it down on his bench when Mr. Krabs and Spongebob come to visit them. He goes up to the bars, and in a few shots, when it cuts to him, you can see the bench he was just on and the pencil has disappeared.
Answer: I believe this is the Season 6 episode "Spongicus".