Magic Show / 24 Hours to Live - S1-E18
Continuity mistake: The boarding house has a downstairs bathroom, but in "Gerald Comes Over", there's only one bathroom and it's upstairs.
Love and Cheese / Weighing Harold - S4-E7
Continuity mistake: Love and Cheese: When Arnold and Lila's boat starts sinking, it starts to move backwards and hits a huge rock at the edge of the waterfall. When Lila almost falls and Arnold holds her up, the rock is gone. It reappears in the following shots. (00:10:07 - 00:10:40)
Grandpa's Sister / Synchronized Swimming - S4-E12
Continuity mistake: Synchronized Swimming: In the pool scene at the beginning, we see a close-up shot of Connie and Maria. In the next shot, they are nowhere to be found. The three kids surrounding the pool in the beginning also disappear. (This happens because the opening shots are reused from the episode "Sixth Grade Girls.") (00:12:01)
Runaway Float / Partners - S2-E20
Continuity mistake: Runaway Float: When the beeper float first starts to speed out of control, in one of the shots, Helga is wearing her regular outfit, not her beeper costume. On top of that, the kids on the float are smiling and waving, not freaking out like they were before. (00:08:39)
Runaway Float / Partners - S2-E20
Continuity mistake: Runaway Float: When Arnold stands up on the bike before jumping onto the parade float, Eugene's hair disappears mid-shot. (00:10:11)
Coach Wittenberg / Four-Eyed Jack - S2-E16
Continuity mistake: Coach Wittenburg's anchor tattoo changes color from red to purple in between shots.
Suggested correction: No, his tattoo is always red.
False Alarm / World Records - S1-E17
Continuity mistake: In "World Records", during Arnold's inspirational speech on the stoop of the boarding house, Gerald is sitting on the railing. He changes positions from sitting facing Arnold on the steps to facing the street between shots.
Save The Tree / New Teacher - S2-E1
Continuity mistake: In the beginning of 'Save The Tree', the tree ladder is a distance above the ground. Later on in the episode, when Arnold and his friends go to the tree house for the last time, the ladder is practically touching the ground.
Save The Tree / New Teacher - S2-E1
Continuity mistake: When Harold eats Mr. Simmons' tomato sandwich, there is a red stain from the tomato on Harold's desk. This stain disappears in later shots.
Weird Cousin / Baby Oskar - S4-E11
Continuity mistake: In "Baby Oskar" the apartment number on the door to Oskar and Suzie's apartment appears and disappears multiple times throughout the episode.
Weird Cousin / Baby Oskar - S4-E11
Continuity mistake: In "Baby Oskar" when Suzie answers the phone there are 12 buttons on the phone, but when she is sitting on the bed there are 9 buttons.
Arnold & Lila / Grand Prix - S3-E13
Continuity mistake: When Arnold, Sid, Eugene, and Stinky are arguing about the name of the go cart the name is already painted on. (00:17:20)
Runaway Float / Partners - S2-E20
Continuity mistake: The kids' teacher in this episode is Miss Slovak, who was their teacher in the first season, but in the first episode of this season they had a new teacher, Mr. Simmons.
Suggested correction: Other than the few episodes that take place at a specific time; this series was not meant to be taken in chronological order. Just roughly during the same 4th grade school year.
Part-Time Friends / Bio Square - S2-E19
Continuity mistake: The kids' teacher in "Bio Square" is Miss Slovak, who was their teacher in the first season, but in the first episode of this season they had a new teacher, Mr. Simmons.
Suggested correction: Other than the few episodes that take place at a specific time; this series is not meant to be taken in chronological order. Just roughly during the same 4th grade school year.
Save The Tree / New Teacher - S2-E1
Continuity mistake: In New Teacher when the principal is telling the class about their new teacher the students switch seats between shots.
Olga Comes Home / Sally's Comet - S1-E15
Continuity mistake: In Sally's Comet when Gerald, Arnold, and Grandpa are in the traffic jam on the way to Hawk Mountain the position and type of cars around them change. When we first see the car there is a truck there and no room for them to turn around. When they do turn around then there is room and the truck is gone.
Continuity mistake: The pets OK sign on Arnold's house changes in different episodes.
Continuity mistake: When Helga is talking about Arnold, the computer store she is in front of is on a corner (Phoebe is seen going around the corner) but a few shots later the store is no longer on a corner.
The List/Haunted Train - S1-E8
Continuity mistake: At the beginning of The Haunted Train Grandpa's ice cream changes color from orange to white.
Helga's Locket / Sid and Germs - S5-E7
Continuity mistake: When Sid decides to be a slob again, he picks up his frog and you can see that he has gloves on. When the following shot shows a close-up of the frog in Sid's hand, the hand holding the frog does not have gloves on.
