Grandma's Kisses / Squidville - S2-E9
Continuity mistake: When Squidward parks his bike next to the store, he goes inside, and when he goes outside, his bike is gone.
Grandma's Kisses / Squidville - S2-E9
Audio problem: After SpongeBob causes a flood in his grandma's house, he cries because he is fed up of being an adult and his grandma tells him he doesn't have to be a baby to get her love. When SpongeBob replies, "I'm not?" note that in his reflection, his mouth does not move.
Grandma's Kisses / Squidville - S2-E9
Continuity mistake: In Squidville, Spongebob and Patrick are at the front gate and when Spongebob says, "But you just ate 3 orders of fried oyster skins," Spongebob's teeth disappear.
Grandma's Kisses / Squidville - S2-E9
Continuity mistake: In Squidville, when Spongebob and Patrick are using their reefblowers, Squidward changes from his dancing clothes into normal clothes in the next 2-4 shots when he is digging out of his house.
Grandma's Kisses / Squidville - S2-E9
Continuity mistake: When Spongebob stops crying, his grandma pulls a plug out of the floor to drain the water, but in a later shot through a window, the plug and hole are gone.
Grandma's Kisses / Squidville - S2-E9
Continuity mistake: Spongebob's watch appears and disappears between shots.
Grandma's Kisses / Squidville - S2-E9
Continuity mistake: When Squidward enters Squidville, he is looking for apartment number 304. When he is looking for his apartment, the numbers on the doors disappear and re-appear.
Grandma's Kisses / Squidville - S2-E9
Continuity mistake: When SpongeBob and Patrick had used the reef blower to take parts of Squidward's house off, they had taken off all parts but the two ear-like parts on the sides of the house. When Squidward demands that they put the parts back, the ear parts are no longer on the house, but are being blown back onto the house. This isn't possible because they were never taken off in the first place.
Grandma's Kisses / Squidville - S2-E9
Continuity mistake: When Patrick is asleep,after several scenes SpongeBob begins to cry,his Grand-mom calms him down and unplugs a plug,but Patrick is nowhere to be seen.
Grandma's Kisses / Squidville - S2-E9
Deliberate mistake: Spongebob and Patrick sucks the windows off Squidward's house using leafblowers. The holes in the wall that the windows were in magically disappear.
Grandma's Kisses / Squidville - S2-E9
Continuity mistake: When Spongebob and Patrick first arrive at the crowd, there's a window on the wall next to them. After they mistake that one octopus for Squidward, the window has vanished.
Grandma's Kisses / Squidville - S2-E9
Other mistake: At the end of Grandma's Kisses, Harold "Bill" is olive green.
Answer: I believe this is the Season 6 episode "Spongicus".