Grandma's Kisses / Squidville - S2-E9
Other mistake: At the end of Grandma's Kisses, Harold "Bill" is olive green.
Mermaid Man and Barnacle Boy IV / Doing Time - S3-E1
Other mistake: When the citizens pop out of Sponge Bob's holes near the end of Mermaid Man and Barnacle Boy 4, if you look closely, Sandy's head is gone except her eyes and nose.
Chum Bucket Supreme/Single Cell Anniversary - S6-E22
Other mistake: In Chum Bucket Supreme, when Plankton is changing his sign for his restaurant, the door to the Chum Bucket is missing. (00:01:10)
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.
You Don't Know Sponge/Hide and Then What Happens - S8-E3
Other mistake: It is revealed in this episode that Patrick is right-handed. However in the episode "Krusty Towers", when asked to sign the Krusty Towers guest register, he is shown doing so with his left hand.
Mermaid Man and Barnacle Boy / Pickles - S1-E6
Other mistake: In the end credits for the episode "Pickles", Bubble Bass is named "BubbleBass" (without a space).
MuscleBob BuffPants / Squidward, the Unfriendly Ghost - S1-E11
Other mistake: When Squidward is on the royal bed, Spongebob's Pineapple is nowhere in sight.