Selling Out/Funny Pants - S4-E5
Continuity mistake: In "Selling Out", at the end, all the customers leave the Krusty Krab. But when the Krusty Krab floods, the place is packed with customers.
Selling Out/Funny Pants - S4-E5
Continuity mistake: In "Selling Out", Mr. Krabs hears the footsteps of many customers approaching and the shot shows the entrance to the Krusty Krab from the inside, with no one in sight. When Mr. Krabs tells the guys that they're coming, it shows Squidward in a few shots mopping right in front of the doors, even though he wasn't seen there previously.
Selling Out/Funny Pants - S4-E5
Audio problem: In "Selling Out", Mr. Krabs explains to Spongebob that he's retiring. When he says "bowls of fruit", his mouth doesn't match the movements.
Selling Out/Funny Pants - S4-E5
Continuity mistake: In "Funny Pants" when Mr. Krabs tells SpongeBob to touch the money the anchor on the door is yellow. In the next shot, it is red, like it is in other episodes.
Selling Out/Funny Pants - S4-E5
Continuity mistake: In "Selling Out" when the Krabby O'Mondays is just about to flood, SpongeBob and Squidward have their Krusty Krab hats on. About ten seconds ago, they had their Krabby O' Mondays' hats on.
Answer: I believe this is the Season 6 episode "Spongicus".