Continuity mistake: In "A Flea in Her Dome", Patrick gets bitten by a flea and his chest is covered in bites. He takes out a pencil and connects some of the dots to make a horse. A few shots later, the horse and the bites disappear.
Continuity mistake: In "Giant Squidward", Squidward goes to spray his wilting kelp with fertilizer and sets down a watering can right next to him. When the kelp goes back to normal in the next shot, the watering can disappears and is not seen again.
Continuity mistake: In "Hall Monitor" when SpongeBob is pretending to be the "open window bandit," you can see a red piece of coral outside of the house that he is about to break in to. When he jumps through the open window, frightens the people inside, and they run out of the house, the red piece of coral is gone.
Continuity mistake: In "Jellyfishing" when Squidward comes home in the bed thingy, the king jellyfish hovers above him. At first, Squidward is facing his house. But in the next shot, he is facing the road. When he replies "Ow" he is facing his house again.
Continuity mistake: The scene in episode Rock-a-Bye Bivalve where SpongeBob and Patrick start arguing about working for Junior at Patrick's house, SpongeBob is not inside the house. While SpongeBob is staring down at Patrick, his head is sticking out of the top of the hole in the ground. Once SpongeBob jumps in the top of the hole is way past their head.
Continuity mistake: In "Fools in April", Squidward put some paper towels in his ears to block out the noise of Spongebob's laugh echoing throughout the Krusty Krab. He covers his ears, and in the next shot, the paper towels are missing and not in his hands.
Continuity mistake: In "Fools in April", Gary is sleeping next to his food bowl in the first shot, with Spongebob's bed nowhere to be seen. After hearing Spongebob's voice, Gary wakes up. In the next shot, Gary's food bowl is sitting in front of Spongebob's bed post.