Jellyfishing / Plankton! - S1-E3
Continuity mistake: At the beginning of Plankton., Plankton is very small. Later in the episode, as in the rest of the show, he's bigger and not that small.
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.
Fools in April / Neptune's Spatula - S1-E19
Continuity mistake: Eventually after Spongebob takes the door wheel handle off, it comes back.
Jellyfishing / Plankton! - S1-E3
Other mistake: In "Jellyfishing", when SpongeBob and Patrick walk back to their houses covered in bandages, when SpongeBob says "Hey, Patrick." Patrick is mouthing what SpongeBob says.
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.
Sandy's Rocket / Squeaky Boots - S1-E8
Continuity mistake: When SpongeBob is explaining why he thinks there are aliens in Sandy's Rocket, you can see a plant and rocks. We see a wide shot and it has now disappeared. (00:02:00)
Pizza Delivery / Home Sweet Pineapple - S1-E5
Continuity mistake: After Spongebob's house is gone, Squidward boo-hoos and goes into his house, then sounds happy. He starts throwing streamers and confetti out of his NOT-OPEN porthole. If the porthole was closed, they wouldn't fly out. Similar to some other ones in this show, and one in Fairly Odd Parents.
Culture Shock / F.U.N. - S1-E10
Continuity mistake: When SpongeBob and Plankton jellyfish,SpongeBob catches a jellyfish with no spots. Then it shows the jellyfish with spots or vice-versa.
Sandy's Rocket / Squeaky Boots - S1-E8
Continuity mistake: When Pearl is opening her present the cake disappears.
Culture Shock / F.U.N. - S1-E10
Revealing mistake: In "Culture Shock" when Spongebob takes the green fish's order, he has a pencil tucked in his ear, but he doesn't have an ear, so it's just floating in thin air. (00:01:55)
Continuity mistake: In the scene where Mr. Krabs is saying "this is no game" Spongebob is in his underwear, then it goes to Mr. Krabs and back to Spongebob and he's in his work clothes.
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.
Jellyfishing / Plankton! - S1-E3
Continuity mistake: Spongebob, controlled by Plankton, wasn't aiming directly at Squidward's house, but he eventually breaks through the wall.
Suggested correction: He might not have been aiming directly at Squidward's house at that moment, but after that shot, there is a 5-second shot of Squidward in his bed before SpongeBob crashes through his wall. Within those 5 seconds off-screen, there was time for Plankton (who is controlling SpongeBob) to turn SpongeBob towards the direction of Squidward's house.
Hooky / Mermaid Man and Barnacle Boy II - S1-E20
Continuity mistake: Before SpongeBob takes off his pants, his pants are the only thing that is hooked to the fish hook. Later in the scene, his underwear is hooked as well.
Hooky / Mermaid Man and Barnacle Boy II - S1-E20
Continuity mistake: In "Hooky," when Spongebob gets hooked, the hook changes from dark yellow, to dark pink, to dark blue in between shots.
Naughty Nautical Neighbors / Boating School - S1-E4
Continuity mistake: The track changes between days.
Valentine's Day / The Paper - S1-E16
Continuity mistake: In "Valentine's Day", Patrick starts searching his present in the fair. Then he goes to a mountain and falls thinking that there will be his present. This mountain wasn't there before, even when they arrived to the fair.
Naughty Nautical Neighbors / Boating School - S1-E4
Continuity mistake: When Patrick runs out of Spongebob's house after Spongebob cries and says he's cheating, the lower right window beside the door is gone.
Naughty Nautical Neighbors / Boating School - S1-E4
Continuity mistake: When Squidward starts making pink bubbles with messages, he goes to his backyard. Notice he never closed the back window of his house. When he starts laughing because of the messages, suddenly the window is closed. After Patrick saves Squidward, the window is still closed, but when they go to the front of his house, the window is open.