Sandy's Rocket / Squeaky Boots - S1-E8
Other mistake: In the episode "Sandy's Rocket", Spongebob and Patrick go "alien-hunting." SpongeBob and Patrick are in Squidward's house. But when SpongeBob holds the hot water bottle, and he says "No, it's an egg-sack!", one of the drops leaking from the bottle goes up instead of down.
Sandy's Rocket / Squeaky Boots - S1-E8
Factual error: Sandy's dome is both airtight and watertight to keep any water out of the dome and any air inside the dome. When the rocket, positioned outside of the dome, begins to launch, smoke is coming inside the dome. This shouldn't be able to happen if the dome is airtight and watertight.
Sandy's Rocket / Squeaky Boots - S1-E8
Continuity mistake: In "Squeaky Boots", Mr. Krabs starts hearing squeaky sounds everywhere. Then he goes mad, and says he took the boots from SpongeBob. In this point, notice of the restaurant floor's color. Mr.Krabs somehow lifts the whole restaurant but we can still see some floor (where Krab is). Notice that now the color of the floor has changed.
Sandy's Rocket / Squeaky Boots - S1-E8
Continuity mistake: When SpongeBob is explaining why he thinks there are aliens in Sandy's Rocket, you can see a plant and rocks. We see a wide shot and it has now disappeared. (00:02:00)
Sandy's Rocket / Squeaky Boots - S1-E8
Continuity mistake: When Pearl is opening her present the cake disappears.
Sandy's Rocket / Squeaky Boots - S1-E8
Continuity mistake: Sandy's Rocket: When you first see SpongeBob in bed you can see a mysterious glass window on the floor. When Patrick arrives it has vanished, evident in the wide shot.
Sandy's Rocket / Squeaky Boots - S1-E8
Audio problem: In "Sandy's Rocket", when Sandy says "Aliens? Is that what this is about?" her mouth stops moving halfway into her sentence.
Sandy's Rocket / Squeaky Boots - S1-E8
Audio problem: When SpongeBob captures Mrs. Puff, her voice and the inflation sound are out of sync.
Sandy's Rocket / Squeaky Boots - S1-E8
Continuity mistake: In "Squeaky Boots", a piece of Mr. Krabs's foot comes off in a hole in the floor boards. Several shots later, it disappears by itself.
Sandy's Rocket / Squeaky Boots - S1-E8
Continuity mistake: In "Squeaky Boots", Mr. Krabs is about to reach a curve in his boat, but in the next shot, he continues driving straight.
Answer: I believe this is the Season 6 episode "Spongicus".