Big Pink Loser / Bubble Buddy - S2-E3
Revealing mistake: Big Pink Loser: When Patrick is answering phone calls, the third time he picks up and says, "No, this is Patrick", the anchor symbol on his hat vanishes for one frame. (00:04:36)
Whatever Happened to SpongeBob? (WhoBob WhatPants) - S5-E18
Continuity mistake: Near the beginning, Spongebob picks up Gary, and some of his slime falls on the floor. When he hugs him and breaks his shell, the slime is gone.
Have You Seen This Snail? - S4-E3
Revealing mistake: After SpongeBob tells Patrick, "I can't find Gary," text that reads "Rough Draft Korea" briefly appears on screen during the bubble transition. (00:08:24)
The Snowball Effect / One Krabs Trash - S3-E3
Other mistake: One Krab's Trash: When Mr. Krabs sticks the ghost drawing in Spongebob's window with the fishing rod, the shadow of the paper is visible on Spongebob, but there is no shadow of the fishing line holding it up.
Bummer Vacation/Wigstruck - S4-E14
Other mistake: Bummer Vacation: When Spongebob says, "You're right, Gary. It is unhealthy to think of the Krusty Krab while I'm on vacation," his legs are missing.
Trivia: In "Where's Gary?" when Spongebob takes the Dirty Bubble Challenge, look closely at the paddleball box; it has the Nickelodeon logo on it.
Revealing mistake: In "Patrick! The Game," when Squidward holds out the notepad it's obviously written on. Just when the bubble transition comes, the notepad clears itself.
Help Wanted / Reef Blowers / Tea at the Treedome - S1-E2
Continuity mistake: In "Help Wanted", the last time SpongeBob says "I'm ready!", his collar turns red.
Jellyfishing / Plankton! - S1-E3
Continuity mistake: In "Jellyfishing", Patrick and Spongebob slide down two ropes and burn their hands on them. The two shots after they land show them trying to cool down their hands and in the shot after that, the ropes they had just slid down on have disappeared.
Chosen answer: You need to provide a little bit more information to be able to answer a question like this. In what region is it not being shown? I see it being replayed here in Australia fairly frequently. As for a general reason, there does not appear to be any for why it specifically might have been taken off the air in any country or region. Like any show certain episodes can sometimes not be replayed for long periods for unknown reasons.
Lummie ★