
The Secret Box / Band Geeks - S2-E14
Continuity mistake: In Band Geeks during the Day Two scene, in the beginning you can see Pearl near the front, but in the distant shot that follows Pearl has moved further back. (00:04:20)

The Krabby Patty That Ate Bikini Bottom/Bubble Buddy Returns - S8-E15
Continuity mistake: At the beginning of Bubble Buddy Returns, right after SpongeBob reads the letter from Bubble Buddy, Gary's swirl is blue and his spots are red.
Nasty Patty / The Idiot Box - S3-E4
Continuity mistake: In "The Idiot Box", Spongebob and Patrick are standing on the curb of the street and there is a building in the distance. Several shots later, they are standing in the same spot, but the building has disappeared.
Texas / Walking Small - S1-E18
Continuity mistake: In "Walking Small", The eel that stole Spongebob's ice cream cone throws it at his face. Different shots some show ice cream on Spongebob's nose, and some show that Spongebob's face is clean.
Your Shoe's Untied / Squid's Day Off - S2-E2
Continuity mistake: Near the start, at first you can see words on the menu board, then you can't. (00:05:50)
Bummer Vacation/Wigstruck - S4-E14
Continuity mistake: In Wig Struck, Patrick takes a bite out of Spongebob's wig and in the next shot, the wig is restored.
Continuity mistake: SpongeBob is holding a picture of Plankton and Mr. Krabs, then when he pulls Plankton and Mr. Krabs together, the picture disappears.
House Fancy/Krabby Road - S6-E1
Continuity mistake: In House Fancy, Squidward gets a bad sofa injury. In the next shot, his feet seem fine.
Continuity mistake: Throughout the whole episode of "Missing Identity", SpongeBob's shirt is backwards. This is seen with his sleeves being supposedly behind him. The sleeves are missing from the front, which is normal, but throughout the episode, pay attention to behind SpongeBob. His sleeves are supposed to be behind him, but are missing altogether.
No Weenies Allowed / Squilliam Returns - S3-E6
Continuity mistake: At the beginning of "Squilliam Returns," Squilliam is walking to Squidward from the left of the garbage pails. When Squidward throws his hat out, Squilliam is to the right of the garbage pails.
No Weenies Allowed / Squilliam Returns - S3-E6
Continuity mistake: In "No Weenies Allowed," when Spongebob gets punched by Patrick, he doesn't have a black eye. When the shot zooms to Spongebob's face, he has a black eye.
Big Pink Loser / Bubble Buddy - S2-E3
Continuity mistake: The broom that Patrick throws on the ground in Big Pink Loser disappears soon after.
Scaredy Pants / I Was a Teen-age Gary - S1-E13
Continuity mistake: When Spongebob is cutting his Jack-O-Lantern, he cuts out an eye on his right, but in the shot from inside the pumpkin the eye hole is gone, then the eye reappears.
It Came from Goo Lagoon - S9-E7
Continuity mistake: The apparel of the fish at the top of the water-skiing pyramid at the start changes between shots.

No Free Rides / I'm Your Biggest Fanatic - S2-E10
Continuity mistake: No Free Rides: When SpongeBob's boat is falling towards the police car, SpongeBob rips off the top part of Mrs. Puff's ski mask, leaving the bottom half of it on her. In the next shot, it disappears, and her regular outfit is shown. (00:11:12)
Patrick SmartPants/SquidBob TentaclePants - S4-E8
Continuity mistake: SquidBob TentaclePants: When the mixed-up SpongeBob and Squidward come out of Sandy's matter transporter, Squidward's arm is on the left, and SpongeBob's arm is on the right. Later on at the Krusty Krab, in the shot after Mr. Krabs tells both of them, "Alright, that's it!", we can see that both arms are SpongeBob's, when the left one is supposed to be Squidward's. (00:17:42)
Bubblestand / Ripped Pants - S1-E1
Continuity mistake: Bubblestand: When SpongeBob comes out of his house at the beginning, he leaves his front door open. Later on, when Patrick's rock opens up, the front door to SpongeBob's house is completely missing. Then, when SpongeBob hands Patrick the bubble wand, the door is back, and it is now closed. Finally, when SpongeBob and Patrick walk into the house later on, the door is open again. (00:02:30)

Hall Monitor / Jellyfish Jam - S1-E7
Continuity mistake: Hall Monitor: When SpongeBob sees the open window to the house, the window is opened to the left. When the two fish run out of the house after SpongeBob scares them, the window is opened the opposite way, then reverts back in the next shot. (00:05:19)
New Student Starfish / Clams - S3-E14
Continuity mistake: New Student Starfish: Spongebob shows Patrick the Good Noodles board when they enter the classroom. Then when Patrick is trying to tell the class his name, the number of stars on it change, and the name "Rich" appears on it, which wasn't there before. Later on, when Spongebob and Patrick are in detention, the names on the board are completely different in some shots. (00:02:48 - 00:11:24)

Continuity mistake: Rock Bottom: When the cardboard version of Spongebob next to the candy machine is shown, it is frowning, but it turns into a smile when it falls over. (00:18:48)
Answer: I believe this is the Season 6 episode "Spongicus".