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.
Ghost Bride / Gerald v.s. Jamie O. - S5-E21
Corrected entry: The boys get locked in the cemetery by Helga so she can prank and scare them. Problem here is surely cemeteries lock up by a certain time, so it would've been locked before they arrived.
Correction: Not all cemeteries open and close at the same time.
That is very true. It should also be noted that not all cemeteries have overnight security or padlocked gates. So even if the cemetery was closed, the kids could still get in if this was a cemetery that isn't heavily surveilled.
Downtown as Fruits / Eugene's Bike - S1-E1
Corrected entry: In the teeter-totter scene, Gerald's shirt is number 3 instead of 33.
Correction: This scene took place years before, at what looks like day care. So it would be a different shirt than the one he has now and could easily have a different number on it.
Tutoring Torvald / Gerald Comes Over - S1-E13
Continuity mistake: In Gerald Comes Over, Gerald says whenever he goes to Arnold's house he always goes straight to Arnold's room and has never seen all of Arnold's house. Also he seems never to have met any one else that lives there, but in previous episodes we have seen him in other parts of Arnold's house and met many of the people that live there.
Suggested correction: Other than the few episodes that take place at a certain time; this series is not meant to be taken in chronological order. Just roughly during the same 4th grade school year.
The Aptitude Test / Oskar Gets a Job - S3-E9
Plot hole: When Eugene dropped the tests, just about all of them fell out of their folders, but apparently only Harold and Helga's were switched.
Suggested correction: We don't know that definitively. Those were just the only two caught as the teacher noticed their tests were very off from who they were as students. He didn't appear to check any of the others for mix ups.
Bag of Money / Principal Simmons - S5-E4
Continuity mistake: Iggy removes his sunglasses - twice.
Suggested correction: The first time he is holding his glasses there was time for him to remove them we just did not see it. The second time we see him remove them.
Crabby Author / Rich Kid - S3-E17
Continuity mistake: In "Rich Kid" Lorenzo is introduced as a new student, but he was in a previous episode titled "Arnold's Room."
Suggested correction: Other than the few episodes where a specific time of year is taking place; these episodes are not meant to be taken to be shown in chronological order. Just roughly in the same 4th grade school year.
Tutoring Torvald / Gerald Comes Over - S1-E13
Continuity mistake: Arnold switches from his left hand to his right hand when taking the test.
Suggested correction: I don't believe it is ever established whether Arnold is left or right-handed in the series. Without confirmation; he may very well be part of the ambidextrous population that uses both. I used to write with both hands myself in school.
Except the mistake is saying he switches hands in between shots during the test. Not that one episode he's left handed and the next he's right handed. Yes, the teacher was shown for about 1-2 seconds before the switch happened. But these mistakes should be considered valid as an actual mistake in animation rather than to suggest to the audience that for no reason whatsoever, Arnold switches hands to finish the test, and only does so when not seen.
I'm ambidextrous myself, and I often switched hands when taking tests. It was very useful for preventing hand cramps. It only takes a couple of seconds to switch the pencil to the other hand, so I don't see why Arnold can't do it within that span of time too.
I do believe he is ambidextrous. In "The longest Monday" he is using chop sticks with his right hand. Many other episodes he uses his left hand to write.
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.
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.
Arnold Saves Sid / Hookey - S2-E7
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 have a new teacher, Mr. Simmons.
Suggested correction: Other than the few episodes that take place during a specific time of year; these episodes are not meant to be taken in chronological order. Just roughly in the same 4th grade school year.
Tour de Pond / Teachers Strike - S2-E18
Continuity mistake: The kids' teacher in "Teachers Strike" 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 during a specific time of year; these episodes are not meant to be taken in chronological order. Just roughly in the same 4th grade school year.
Magic Show / 24 Hours to Live - S1-E18
Audio problem: Helga rides past Arnold in a bus and yells "24 hours until you die!" or something like that. Her mouth never moves- it just stays open in an evil smile.
Suggested correction: Although it's hard to make out, her mouth is moving when she says that. Also, she says "23 hours until you die!" not 24.
Arnold's Thanksgiving - S3-E14
Continuity mistake: When Joey is shown in close-up, his missing tooth looks like it's there but it's covered with something black and his missing tooth keeps reappearing and disappearing in the last scenes.
Suggested correction: Joey never appears in this episode.
Arnold Saves Sid / Hookey - S2-E7
Revealing mistake: Arnold and Gerald's lockers don't have padlocks, like most of the others do.
Suggested correction: Like you state, most of the other lockers have padlocks, which means that some don't. You can even see some lockers without padlocks in the beginning. This is not a reason as to why Arnold and Gerald's lockers having no padlocks is a mistake. It more has to do with the fact that their lockers in particular should have padlocks, because they usually have them in other appearances. Edit: While I do agree with what I said, I now think that changing the mistake's wording would have been a better option than adding a correction, as Arnold and Gerald's lockers not having padlocks is still a mistake on its own.
The Aptitude Test / Oskar Gets a Job - S3-E9
Revealing mistake: The test paper Eugene put back in Harold's folder is blank.
Suggested correction: The paper is not blank. Helga used a purple pen to fill in her paper, and Eugene put it in Harold's folder. The paper is filled with purple ink.
