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. (00:05:55)
Boating Buddies/The Krabby Kronicle - S6-E9
Other mistake: In "Krabby Kronicle," when the two scientists exit Sandy's air dome, there are bubbles trailing behind them.
Gullible Pants/Overbooked - S6-E19
Other mistake: In the episode where SpongeBob has to do 3 things in 1 night, near the end, they all get frustrated for not doing their tasks. Look at Mr. Krabs. He runs over to SpongeBob and behind him is bubbles. Impossible, because in Sandy's dome is air.
Gullible Pants/Overbooked - S6-E19
Other mistake: In Overbooked, when Patrick tells Sponge-Bob about his birthday, Sponge-bob put a Krabby patty in his pants. In the next scene when you see Sponge-Bob, the patty is gone.
Chum Bucket Supreme/Single Cell Anniversary - S6-E22
Other mistake: In Chum Bucket Supreme, when Plankton is changing his sign for his restaurant, the door to the Chum Bucket is missing. (00:01:10)
Someone's in the Kitchen with Sandy/The Inside Job - S7-E3
Other mistake: In the kitchen when Plankton asks, "In approximately how long do you cook a patty?" Spongebob's eyelashes are missing.
You Don't Know Sponge/Hide and Then What Happens - S8-E3
Other mistake: It is revealed in this episode that Patrick is right-handed. However, in the season 4 episode Krusty Towers, when asked to sign the Krusty Towers guest register, he is shown doing so with his left hand.
The Krabby Patty That Ate Bikini Bottom/Bubble Buddy Returns - S8-E15
Other mistake: Mr. Krabs pours Sandy's growth serum on a patty. It grows, and Spongebob scrapes some off to construct individual patties from the larger one. The larger one then continues to grow, but the individual ones do not, even though they are all the same meat.
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 ★