Giant Squidward/No Nose Knows - S6-E7
Continuity mistake: In "No Nose Knows", Patrick is trying out his new nose. He passes through a cloud of perfume sprayed by a fish in front of the perfume shop. In the next shot, the fish and the perfume shop are gone.
Gullible Pants/Overbooked - S6-E19
Continuity mistake: In "Gullible Pants" when Mr. Krabs is about to exit the Krusty Krab, he looks at his watch, which disappears in the next shot.
Penny Foolish/Nautical Novice - S6-E2
Continuity mistake: In "Penny Foolish" around the beginning, SpongeBob does a lot of stunts before he picks up the penny. Then when Mr. Krabs flashbacks to what SpongeBob did, the buildings in the background change.
Penny Foolish/Nautical Novice - S6-E2
Continuity mistake: In "Penny Foolish" when Mr. Krabs is driving at night, there are a bunch of buildings surrounding him. Then when the shot cuts to the steering wheel and back to Mr. Krabs the buildings disappear.
Gullible Pants/Overbooked - S6-E19
Other mistake: In Overbooked, when Patrick tells Sponge-Bob about his birthday, Sponge-bob put a Krabby patty in his pants. In the next scene when you see Sponge-Bob, the patty is gone.
Answer: I believe this is the Season 6 episode "Spongicus".