The Fiendish Five, Part 1 - S1-E9
Revealing mistake: After Joey and Tristan fail to remove the sword, Tristan asks Yugi to remove it instead. While he is asking, "Yugi, why don't you give it a go?", his eyes don't appear to be aligned with where Yugi is standing. Yugi is standing at the bottom of the stairs in front of Tristan, but Tristan is looking to the left. (00:10:35)