Survival of the Idiots / Dumped - S2-E8
Continuity mistake: In the episode "Survival of the Idiots," when Sandy wakes up in Spring and goes outside, the first time we see Patrick and SpongBob standing side by side, SpongeBob is to our left, but later when SpongBob is trying to make up an excuse, they've swapped places.
Survival of the Idiots / Dumped - S2-E8
Continuity mistake: In Dumped, when Patrick is finished brushing his teeth, his toothbrush disappears.
Survival of the Idiots / Dumped - S2-E8
Continuity mistake: In "Dumped", when Gary takes Patrick's cookie they are in the laundry room. When SpongeBob wants to take Gary for a walk, they instantly appear in the living room. SpongeBob also has a leash in his hand. There is no time for them to walk from the laundry room to the living room.
Survival of the Idiots / Dumped - S2-E8
Continuity mistake: When the winter ends, there's a shot of Sandy's tree, and there's no window in it. When Sandy sees SpongeBob and Patrick, suddenly the tree has a window. A very noticeable mistake.
Answer: I believe this is the Season 6 episode "Spongicus".