Erratas in the Anime

[Pyro]

It's not a huge issue in the original show, but it became noticeable in GX when card effects started changing to more suit the OCG/TCG in real life (as well as the rules and ban lists, like the lack of Pot of Greed in later GX). One example that always springs to mind is my favorite trap, Crush Card, which was used in season 3 and had its then-TCG accurate effect of only lasting for 3 turns rather than the broken OG effect when Kaiba used it. There were some weird happenings in the original, like Soul Exchange having a different effect in the Alister duel, but it wasn't as blatant as what went down in GX.

Did you notice any effect changes in the anime? From an in-universe perspective, why do you think this stuff happened?

 

[Papasmurf]

I remember Magic Cylinder having its effect changed to the TCG effect before being changed back to the less-powerful effect used in Battle City in the Yugi vs. Jaden duel. Of course, it was probably done to prevent Jaden from losing instantly when he took 6300 damage to his life points, but it is interesting to note that he did technically time travel to a time before the end of the original series.