Other mistake: At the very end, Sandy puts Wormy inside of a glass jar. Not only does she break the bubble surrounding it, there's no way for water not to enter the jar as she holds it sideways. Wormy should be killed.
Grandma's Kisses / Squidville - S2-E9
Other mistake: At the end of Grandma's Kisses, Harold "Bill" is olive green.
Jellyfish Hunters / The Fry Cook Games - S2-E16
Other mistake: When Patrick takes off Spongebob's right shoe to lick, his foot appears to be his left, not his right. (00:22:05)
Procrastination / I'm With Stupid - S2-E19
Other mistake: I'm With Stupid: When Patrick and his "parents" make fun of Spongebob because they believe he's stupid, he gets so frustrated that he runs through the wall, leading him right outside. This makes no sense, because they are in Patrick's house and the inside of it is underground. (00:21:35)