The Great Snail Race / Mid-Life Crustacean - S3-E15
Continuity mistake: In The Great Snail Race, Gary wipes out into the tires then fire fighters come and put him out (still near the tires) but in the wide shot Gary is back on the track.
The Great Snail Race / Mid-Life Crustacean - S3-E15
Continuity mistake: When Squidward looks through a window of SpongeBob's house, Patrick looks through a higher window. An outside shot shows that Patrick is standing in Squidward's shoulders, however, an inside shot shows that Patrick isn't in Squidward's shoulders.
The Sponge Who Could Fly (aka The Lost Episode) - S3-E16
Continuity mistake: After the walk cycles, the color bars change between shots.
The Sponge Who Could Fly (aka The Lost Episode) - S3-E16
Continuity mistake: When the parrot lands the egg on the remote, in the next shot it vanishes.
The Sponge Who Could Fly (aka The Lost Episode) - S3-E16
Continuity mistake: On the news one fish had hair. Later it was gone.
The Sponge Who Could Fly (aka The Lost Episode) - S3-E16
Continuity mistake: When the tape pours out of the VCR at the end of the show, Patchy the Pirate gets tangled in it. A shot later, the tape is three times longer than it was the shot before it.
Born Again Krabs (aka A Penny Saved) / Safety Freak (aka I Had An Accident) - S3-E17
Continuity mistake: At the beginning of "Born Again Krabs", it shows the outside sky being orange-ish. But when it shows SpongeBob and Mr. Krabs talking about the old patty, you can see a little blue crack through the window.
Born Again Krabs (aka A Penny Saved) / Safety Freak (aka I Had An Accident) - S3-E17
Audio problem: At the end of "Born Again Krabs", SpongeBob is talking to The Flying Dutchman on the phone. SpongeBob's dialogue isn't in sync with his mouth.
Born Again Krabs (aka A Penny Saved) / Safety Freak (aka I Had An Accident) - S3-E17
Continuity mistake: In "I Had An Accident", Sandy opens the door to show that she was being "attacked" by a gorilla and Spongebob is looking through that door to see the events unfold. But after a couple of shots, the door has closed by itself and Spongebob has to open it again before going outside.
Born Again Krabs (aka A Penny Saved) / Safety Freak (aka I Had An Accident) - S3-E17
Continuity mistake: In "Born Again Krabs", when Mr. Krabs first makes his appearance next to Davy Jones' locker, there is some coral taking up a part of the bottom left corner. In a few shots, that same set of coral has disappeared.
Born Again Krabs (aka A Penny Saved) / Safety Freak (aka I Had An Accident) - S3-E17
Continuity mistake: In "Born Again Krabs", after Mr. Krabs returns from the hospital and the Krusty Krab has their "Grand Re-Opening", there are two big yellow signs on the front windows, but in the next shot from the inside, these signs have vanished.
Born Again Krabs (aka A Penny Saved) / Safety Freak (aka I Had An Accident) - S3-E17
Continuity mistake: In "Born Again Krabs", the doctor taking care of Mr. Krabs drops his clipboard and runs. When the Flying Dutchman appears in the next shot, the clipboard is missing.
Born Again Krabs (aka A Penny Saved) / Safety Freak (aka I Had An Accident) - S3-E17
Continuity mistake: In "Born Again Krabs", Mr. Krabs drops the coins that the Flying Dutchman gave to him on the floor. In a few shots, when the Flying Dutchman comes back, the coins have vanished.
Continuity mistake: When Patchy lifts his eye patch to rub his eye and puts the patch on his right eye. In the next shot the patch is on his left eye.
Continuity mistake: Gary leaves big saliva trails. When Squidward realizes that Gary leaves these saliva trails, we can see that is a trail in front of Squidward's house. When Squidward tells SpongeBob about these trails in the language of the past, we can see that the trail of the saliva has changed: it bigger and almost in all the scenery. After a while, we see that the road goes directly to Squidward's house, to its door. How did the road change, if we haven't seen Gary moving?
Continuity mistake: When Patar heats the squished crab in the fire, it's in his left hand. But in the next shot when he eats it, it's in his right.
Krabby Land / The Camping Episode - S3-E19
Other mistake: In "Krabby Land", Mr. Krabs as "Krabby The Clown" finishes his short speech and goes into his office. When he slams the door, bubbles float up and those bubbles stay motionless in the air for a few frames.
Krabby Land / The Camping Episode - S3-E19
Continuity mistake: In "The Camping Episode", Squidward sets down a blanket to lay under the stars and in a couple of shots, the blanket disappears.
Krabby Land / The Camping Episode - S3-E19
Continuity mistake: In "Krabby Land", Spongebob goes to check his motivational quote and from far away, the page is flipped up. But in the next shot, it is a close up and the page is flat against the stack. In the following shot, the page is flipped up again.
Krabby Land / The Camping Episode - S3-E19
Continuity mistake: In "Krabby Land", Mr. Krabs is in his boat with Spongebob in front of the playground filled with children. After looking through a pair of binoculars, he drops them in front of the boat. However, in the next shot the binoculars are gone.
Answer: I believe this is the Season 6 episode "Spongicus".