Krab Borg / Rock-a-Bye Bivalve - S3-E8
Continuity mistake: In "Rock-a-Bye Bivalve" when Spongebob and Patrick hear the bivalve chirping, the coral that vibrates is bright green and is standing up straight. However, when they find the bivalve and take it out from behind the coral, the coral is dark green and is bent over.
Krab Borg / Rock-a-Bye Bivalve - S3-E8
Continuity mistake: Rock-a-Bye Bivalve: When Patrick gets home from the party after midnight SpongeBob is angry, and as Patrick walks out in the interior shot the front door is wide open on the inside of the home, but in the next exterior shot the front door is wide open on the outside of the pineapple.
Krab Borg / Rock-a-Bye Bivalve - S3-E8
Continuity mistake: Krab Borg: The door to Krabs' office has a porthole in many shots, but after Krabs burns his eyes he rushes out of his office into the eating area, and when he runs past Squidward and SpongeBob the office door is the normal solid door, with an anchor on the exterior side.
Krab Borg / Rock-a-Bye Bivalve - S3-E8
Continuity mistake: In 'Rock-a-Bye Bivalve' Spongebob's front door changes hinge sides. Also at the end suddenly there's a light switch next to the door which wasn't there earlier.
Krab Borg / Rock-a-Bye Bivalve - S3-E8
Continuity mistake: The scene in episode Rock-a-Bye Bivalve where SpongeBob and Patrick start arguing about working for Junior at Patrick's house, SpongeBob is not inside the house. While SpongeBob is staring down at Patrick, his head is sticking out of the top of the hole in the ground. Once SpongeBob jumps in the top of the hole is way past their head.
Wet Painters / Krusty Krab Training Video - S3-E9
Continuity mistake: When Mr. Krabs Gets Home, there is a light switch by the door, but in the next shot there is a sign instead.
SpongeBob's House Party (aka Party Pooper Pants) - S3-E10
Continuity mistake: When Spongebob comes home after being arrested, he picks a spare key up from under his mat and gets angry at himself for trying to break in the night before. When he walks in, discomfort on his face, the mat is gone.
SpongeBob's House Party (aka Party Pooper Pants) - S3-E10
Continuity mistake: Patchy's hook hand disappears when he is playing the accordian.
SpongeBob's House Party (aka Party Pooper Pants) - S3-E10
Continuity mistake: When Spongebob comes home from the police station in the morning, he gets the spare key from under the mat. That mat definitely wasn't there last night.
SpongeBob's House Party (aka Party Pooper Pants) - S3-E10
Continuity mistake: When Patchy the Pirate is flying through the houses, he finally hits a pole with nothing on him. Yet when Patchy comes screaming back into his hat, he had a broken window in him and wood through his hat.
SpongeBob's House Party (aka Party Pooper Pants) - S3-E10
Continuity mistake: When Gary and Spongebob are waiting at the door, there is a sign behind him that says "pin the tail on the horace" (yes it says horace), and there is one tail hanging up, but when everybody comes in there are suddenly two.
SpongeBob's House Party (aka Party Pooper Pants) - S3-E10
Continuity mistake: When SpongeBob is locked out of his house, he digs a hole to try and get in. This hole doesn't exist the next morning.
Chocolate With Nuts / Mermaid Man And Barnacle Boy V - S3-E11
Continuity mistake: When SpongeBob and Patrick are pretending that they need an operation and that fish falls down the stairs, if you look at Patrick's head he has no bandage on his head. But when he looks at SpongeBob right after that fish falls down the stairs, a bandage suddenly appears on his head.
Chocolate With Nuts / Mermaid Man And Barnacle Boy V - S3-E11
Continuity mistake: The second time the chocolate guy chases Spongebob and Patrick, they run away and leave all their bags. But, in the next shot, they have their bags with them.
Chocolate With Nuts / Mermaid Man And Barnacle Boy V - S3-E11
Continuity mistake: When Barnacle Boy and E.V.I.L. are hiding behind the rock you can see Barnacle Boy's fingers. In the next shot he is wearing gloves.
Chocolate With Nuts / Mermaid Man And Barnacle Boy V - S3-E11
Continuity mistake: Chocolate With Nuts: While SpongeBob and Patrick are selling chocolate, the elderly female's door opens at the left, but after Patrick claims their chocolate will make you live forever, the door is open the opposite way.
Chocolate With Nuts / Mermaid Man And Barnacle Boy V - S3-E11
Continuity mistake: Mermaid Man And Barnacle Boy V: When Barnacle Boy shouts that he wants to be called Barnacle Man and demands respect, the door to Krabs' office is missing. Then it happens again when the news comes on.
Chocolate With Nuts / Mermaid Man And Barnacle Boy V - S3-E11
Continuity mistake: In 'Chocolate With Nuts' the bandaged up fish's house's front stairs had only a few steps when Spongebob and Patrick approached, but as the fish falls down there's suddenly a lot more.
Chocolate With Nuts / Mermaid Man And Barnacle Boy V - S3-E11
Continuity mistake: In "Chocolate With Nuts", Patrick and Spongebob buy the chocolate holding bags from one man, they walk to the next house next door. When they are standing next to the door, the first house behind them disappears.
Chocolate With Nuts / Mermaid Man And Barnacle Boy V - S3-E11
Continuity mistake: After MermaidMan screams "To Make Out Reef" he accidentally falls over on his chair. When Patrick complains that they aren't gonna get pizza the chair is back up again.
Answer: I believe this is the Season 6 episode "Spongicus".