I semi-recently got the DVD for the SMB3 cartoon, and while I was writing a fanfic spoof of it, I noticed something in the episode "The Beauty of Kootie". In that episode, Bowser tries to steal oil from the Sultan of Desert Hill. It has come to my conclusion that the Sultan's palace basement is magic, because every possible animation error occurs in there. Just read this list.
When Wendy complains, "I told you this was no job for a beauty queen!", her scales flash between tan and orange.
Larry comes in to tell her to "tell that to Mario Bros.", during which his head has somehow changed purple.
After talking to Bowser about it, Wendy complains about his "making her so mad she could spit in his soup", but her wand somehow enlarges itself while she's facing the other direction. Never fear, because it then returns to its normal size as Wendy is putting it back in her shell.
Things take a breather until the human-turned Wendy introduces herself as "Lady Fettuccini Alfredo", during which her eyeballs change blue. (I'm not talking about the pupils.)
A suspicious Luigi tries to get a better look at the tail he is "accusing" "Lady Fettuccini" of having, which somehow changes to the same hue as her skin color when she tail-whips him.
The magic continues with things that appear from out of nowhere, starting with a dinner table that Mario somehow manages to set up while Luigi was trying to get a better look at "Lady Fettuccini"'s back.
After struggling to swallow some spaghetti, "Lady F" suggests bringing the rest of the good guys to a dungeon cell that's just appeared in the background.
So under her suggestion, Mario convinces Toad, Peach (who, strangely, does not seem to show any signs of jealousy about Mario’s new infatuation), the Sultan, and the unnamed servant to go into the cell, after which Wendy yells for Larry to "restore her to her natural loveliness". As she says this, her tail once again changes color, this time to green.
After changing his sister back to her normal state, Larry grabs an oil hose that, you guessed it, wasn't there before, and sends the Mario Bros. down a hole in the floor that also wasn't there before.
Bowser then emerges from a pipe that wasn't in that background before and congratulates his kids as Larry's eyes change orange to match his head being colored brown-orange as his pop was struggling to enter.
As if that weren't enough, his and Wendy's beaks have the same color as their heads right before they begin taunting Peach.
Mario appears out of a pipe that, of course, has just appeared in the background, and when Peach does show a bit of Mario/Peach support for the fans, the usually white-pink part of her dress is colored a darker shade of pink (kind of matching the artwork for the games).
Peach distracts Wendy and Larry so the Marios can grab Larry's wand, which has somehow wound up on the ground, even though he wasn't shown dropping it or putting it down earlier.
The goofs take another break until Wendy puts the moves on "Casanova Koopa", alias Luigi, and she does it by floating on her high heels.
During this, she somehow changes him back to normal, and Cheatsy is so flabbergasted that his head changes orange again.
Wendy stays hovering in midair right before leaping into the air upon her sudden realization. Fortunately, that's the last we see of the basement, so the errors end there.
Now is that basement magic, or are all those goofs just products of bad animation? You decide.