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.
Sandy's Rocket / Squeaky Boots - S1-E8
Other mistake: In the episode "Sandy's Rocket", Spongebob and Patrick go "alien-hunting." SpongeBob and Patrick are in Squidward's house. But when SpongeBob holds the hot water bottle, and he says "No, it's an egg-sack!", one of the drops leaking from the bottle goes up instead of down.
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.
Other mistake: In "SpongeBob and the Clash of Triton," the title card says it is called "Neptune's Party," thus making it a wrong title.
Suggested correction: "Neptune's Party" was the original title for "The Clash of Triton."
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.
Enemy In-Law/Mermaidman and Barnacleboy VI: The Motion Picture - S4-E7
Other mistake: Plankton's phone doesn't have a 0 button on it.
The Chaperone / Employee of the Month - S1-E12
Other mistake: When Pearl is crying in the Krusty Krab, the customers are just the same person over and over and over.
SpongeBob's House Party (aka Party Pooper Pants) - S3-E10
Other mistake: When Patchy pops Minnie Mermaid's pool, water comes out from a different place.
The Snowball Effect / One Krabs Trash - S3-E3
Other mistake: In 'The Snowball Effect' when Squidward attempts to make Patrick and Spongebob resume their snowball fight he throws a snowball at them which they avoid, and it puts out Squidward's fire inside. Squidward had his back towards his house and threw the snowball in the opposite direction.
Other mistake: At the very end, Sandy puts Wormy inside of a glass jar. Not only does she break the bubble surrounding it, there's no way for water not to enter the jar as she holds it sideways. Wormy should be killed.
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.
Other mistake: Always in the older episodes (and sometimes in the newer ones), when a fish in the background takes his/her second bite of a sandwich, the sandwich still looks like the first mark. It does this on every bite after the first.
Jellyfish Hunters / The Fry Cook Games - S2-E16
Other mistake: When Patrick takes off Spongebob's right shoe to lick, his foot appears to be his left, not his right.
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.
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.
Grandma's Kisses / Squidville - S2-E9
Other mistake: At the end of Grandma's Kisses, Harold "Bill" is olive green.
Mermaid Man and Barnacle Boy IV / Doing Time - S3-E1
Other mistake: When the citizens pop out of Sponge Bob's holes near the end of Mermaid Man and Barnacle Boy 4, if you look closely, Sandy's head is gone except her eyes and nose.
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)
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.
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 episode "Krusty Towers", when asked to sign the Krusty Towers guest register, he is shown doing so with his left hand.