Culture Shock / F.U.N. - S1-E10
Continuity mistake: When we first see Squidward in the canyon background, his outlining is gone. Then, in the next shot, it's back.
MuscleBob BuffPants / Squidward, the Unfriendly Ghost - S1-E11
Plot hole: In MuscleBob BuffPants, when SpongeBob first shows off his new inflatable muscles to everyone on the beach, he had the strength to punch two muscular fish into the air with them. A minute later, he could not even lift a glass of juice with the inflatable muscles. (00:04:25 - 00:05:20)
MuscleBob BuffPants / Squidward, the Unfriendly Ghost - S1-E11
Continuity mistake: When Squidward comes out of the bathroom and sees his melted sculpture, the eyes on the melted sculpture change from looking on the floor to looking up in a matter of seconds.
MuscleBob BuffPants / Squidward, the Unfriendly Ghost - S1-E11
Continuity mistake: When Patrick throws Squidward the watermelon, it lands on his torso and he falls down. When the camera goes back to Squidward, the watermelon is in his mouth.
MuscleBob BuffPants / Squidward, the Unfriendly Ghost - S1-E11
Other mistake: When Squidward is on the royal bed, Spongebob's Pineapple is nowhere in sight.
The Chaperone / Employee of the Month - S1-E12
Continuity mistake: When Spongebob is talking about Annoy Squidward Day, you see a calendar with 28 days, indicating that it's February, but the empty picture on the wall says January.
The Chaperone / Employee of the Month - S1-E12
Audio problem: We see Spongebob in his long legs walk over to Mr. Krabs' house, then we see the door from inside the house. Through the window we see Spongebob's long legs, yet we hear him spring boing his way over when we see them already there.
The Chaperone / Employee of the Month - S1-E12
Continuity mistake: When Spongebob, in his black suit and long legs, is at the door of Mr Krabs', he used a lever to lower himself down. When we cut back to Spongebob, it's gone.
The Chaperone / Employee of the Month - S1-E12
Continuity mistake: When Spongebob is crying next to the employee of the month wall, (just before he says "How could I have let the quality of my work slip so much?") the order of the pictures is messed up. It goes December, February, January. Then, when we see the close-up of Squidward's face laughing, the order is correct again.
The Chaperone / Employee of the Month - S1-E12
Continuity mistake: In "Employee of the Month", when Spongebob is spying on Squidward, Squidward puts his alarm clock to the left of his bed. When Spongebob tries to get the clock, it is now to the right of Squidward's bed.
The Chaperone / Employee of the Month - S1-E12
Continuity mistake: Spongebob says that this is the 27th award he has won, yet when he is standing in front of the pictures there are at least 30.
The Chaperone / Employee of the Month - S1-E12
Other mistake: When Pearl is crying in the Krusty Krab, the customers are just the same person over and over and over.
The Chaperone / Employee of the Month - S1-E12
Continuity mistake: Spongebob absorbs the pink punch making him look pink in 2 shots - one showing him squirting punch out of his nose, but a shot after that shows him yellow.
Scaredy Pants / I Was a Teen-age Gary - S1-E13
Continuity mistake: When Spongebob is cutting his Jack-O-Lantern, he cuts out an eye on his right, but in the shot from inside the pumpkin the eye hole is gone, then the eye reappears.
Scaredy Pants / I Was a Teen-age Gary - S1-E13
Continuity mistake: Spongebob's belt is missing when his clothes are first revealed while dangling in midair.
Scaredy Pants / I Was a Teen-age Gary - S1-E13
Continuity mistake: The Krusty Krab is filled with Halloween decorations during the episode, but when Spongebob jumps to hide in a barrel there are no decorations in sight.
Scaredy Pants / I Was a Teen-age Gary - S1-E13
Continuity mistake: When Spongebob agrees to hear Mr. Krabs' story, their seats come out of nowhere.
SB-129 / Karate Choppers - S1-E14
Continuity mistake: When Spongebob throws the Krabby Patties on Squidward's head there are only 6 of them, later there's at least 8.
SB-129 / Karate Choppers - S1-E14
Continuity mistake: When Squidward is in the white place and crashes through the floor, he doesn't have his clarinet before he crashes through the floor. But when he is in the time machine, he has his clarinet.
SB-129 / Karate Choppers - S1-E14
Continuity mistake: SB-129: When Squidward opens the door to the time machine, the exterior side of the door has a handle at the left side and opens at the left, but the interior side of that door also has the handle at the left side, though it should be at the right side. Then when Squidward activates the machine, the exterior handle is now at the right side and it opens at the right.
Answer: I believe this is the Season 6 episode "Spongicus".