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.
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.
New Bully on the Block / Phoebe Breaks a Leg - S5-E5
Corrected entry: After Phoebe puts hinges on her cast and Helga and Phoebe are in the library. After Phoebe gets away from Helga and hides within the library shelves, she opens her cast and starts scratching her leg. When Arnold sees Phoebe he says to her, " I just saw you open and close your cast." Yet Phoebe never closes her cast.
Correction: He was just trying to say her cast couldn't be real and was also thinking of the fact that if she could snap the cast open she can snap it shut too. Any human in real life might say "open and close" when all they saw was the cast getting opened.
The Big Scoop / Harold's Kitty - S2-E3
Corrected entry: Arnold's phone number is "555-123", but all phone numbers in the USA have seven digits.
Correction: This is true but tv shows, movies, ect. have license to ignore this fact because they could get sued were they to use a real 7 digit number, even if it was accidental, without permission. So this mistake is not valid as the makers have to do this.
Helga's Love Potion / Gerald's Secret - S2-E2
Corrected entry: When Helga goes into her closet, she has quite a few different dresses, but the one she always wears isn't there.
Correction: Of course not, she's wearing it.
Helga Blabs It All / Harold the Butcher - S3-E1
Corrected entry: The dental hygenist's hair changes color from red to brown.
Correction: No, it's auburn. Auburn hair has red highlights in it, so sometimes it looks red sometimes it looks brown.
Arnold Betrays Iggy / Helga and the Nanny - S3-E10
Corrected entry: In Helga's dream, her slippers start out pink, but when Inge goes after the pigeon, they're white.
Correction: It's her dream, not real. Helga can change whatever she wants in two seconds in her dreams.
The List/Haunted Train - S1-E8
Corrected entry: When Arnold sets his alarm clock, it says 5:45 (a little early for bed), but when he puts it on his desk, it's 10:30.
Correction: 5:45 was the time he was setting to wake up, not the actual time. When we see it on the desk we see the actual time.
Benchwarmer / Cool Jerk - S1-E11
Corrected entry: The players are listed by first name on the scoreboard, and their numbers aren't listed, so there's no way of telling which player is which.
Correction: It's pretty well implied in this show that everybody knows who everybody is. So having only names is perfectly ok.
Das Subway / Wheezin' Ed - S1-E12
Corrected entry: The sun is well above the horizon when they leave the theater, but it sets less than 30 seconds later.
Correction: If you look you can see the sun going down when we first see it when they step out of the theater. This is a cartoon so it's perfectly ok to suspend reality for awhile.
Downtown as Fruits / Eugene's Bike - S1-E1
Corrected entry: When Arnold is fixing Eugene's bike, he's not wearing his hat.
Correction: Unless we saw him without his hat a second before this isn't a mistake, even if it's rare for Arnold to not be wearing his hat.
Corrected entry: The first time Arnold tries it, he says five, but Rhonda actually makes six moves; the second time, Arnold says three, but Rhonda counts off four.
Correction: That's a mistake she made as a character. Not a movie mistake.
Parents Day - S5-E6
Corrected entry: In the first scene where she's shown, Harold's mother is a brunette, but after that she has her normal brownish hair color.
Correction: This entry seems somewhat silly, as brunette means brown hair.
Corrected entry: In the opening credits, when all the boys (led by Arnold) are walking down the alleyway, on our right, Harold looks like he's about to walk straight into a bin. After the girls have done their strut, we cut back to the boys - and there is no bin behind Harold.
Correction: Actually this was Ruth that happened with. Anyways when we see the girls in the alley again (where the bin last appeared) the bin is indeed behind Ruth. You can see it where the back part of the alley is lighted.
Corrected entry: When the people in the buildings yell "Arnold", Sid and Eugene have switched places.
Correction: The way they were when we saw them walking on the street yes. But when this happens the boys are in the alley. Since we haven't seen Sid or Eugene in the alley previously there's no mistake in where they're standing.
Corrected entry: At the end of the first training scene (when Arnold first tries to catch the fly), one of Arnold's feet has no toes; also, just before Arnold falls down the chimney, he has three arms.
Correction: No he doesn't have three arms. You are either mistaking his foot when it pops up for a third arm or your mistaking his two arms for three when we see his arms move quickly and the cartoonist make it look a little like he has more than two arms to show his falling like they often do in cartoons.
Mud Bowl / Gerald Moves Out - S2-E9
Corrected entry: How did the fifth graders manage to forget how to score touchdowns, considering that they scored six or seven in the first half and none of Arnold's special plays were for when his team was on defense?
Correction: They scored much more than that before Arnold's special plays were done. They got 42. They didn't score any when Arnold's special plays were done because they weren't used to them, and they were pretty tricky.
Part-Time Friends / Bio Square - S2-E19
Corrected entry: Towards the end of "Bio Square," Arnold and Helga manage to escape drowning in the titular Square (from a haywire sink leak) by jumping onto her inflatable mattress. The two ants from an experiment by Arnold manage to escape, too, by jumping off a table and onto a floating, half-eaten potato. However, at the end of the episode, when Arnold and Helga are describing their adventure before their science class, Arnold says that the ants "climbed onto the leaf." Knowing how sharp Arnold is, it's unlikely that he mistook the potato for a leaf. This is a simple script error.
Correction: Sharpness aside, Arnold is prone to making errors or mistakes. The two were about to drown and the seriousness of the situation might have mistaken him. Also at that point I don't believe there was anything to prove if he even knew the ants made it to safety so he might have believed they climbed onto a leaf. In any circumstance its at best a character mistake.
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.