Welcome to Duel Academy - S1-E1
Revealing mistake: When Jaden is running through the park at the start of the episode, there is an overview shot of him running past some people. The people are completely still and motionless in the shot. (00:00:10)
Revealing mistake: When Chazz summons Reborn Zombie in Defence Mode, the monster appears on the duel field, as well as the playing card beneath it, positioned at a horizontal angle, for it to stand on. The card casts a shadow on the ground, but the shadow can be seen lifting above the ground. (00:11:22)
Revealing mistake: When Alexis places her Blade Skater card on her duel disk, there is a brief frame where the cards on her duel disk pass above her hand. (00:13:09)
Revealing mistake: Right before Jaden and Chazz start the duel, in the shot of Crowler saying "Indeed, and in front of the whole school too", there are two Slifer Red students who appear to be standing completely still and motionless. (00:09:43)
Revealing mistake: When Chazz summons X-Head Cannon and Z-Metal Tank to the field, he is shown standing completely still, without any body movement in sight. He was in the middle of summoning monsters, so he shouldn't have been standing still like that. (00:13:02)
Revealing mistake: When Jaden says "I got a whole army of vicious army of monsters in my deck just waiting to get at you", a small animation glitch occurs in the bottom right corner of the frame. Just as he begins saying "waiting", he moves his left arm slightly, and part of the red colouring on his blazer disappears from shot, almost as if the animators forgot to colour it in. (00:15:27)
Revealing mistake: When Syrus and Bastion walk onto the arena field to congratulate Jaden, there are extras animated in the background who are cheering yet appear frozen and not moving in any way. (00:18:24)
Revealing mistake: When Jaden says he's started hearing voices again, it cuts to a close-up of a flashback showing Jaden holding the Winged Kuriboh card. The shot appears to be flipped as the LIGHT symbol on the card, as well as the illustration of the card is reversed, compared to every other time this card is shown. (00:03:20)
Revealing mistake: When the duel begins, the Shadow Duelist goes first. He has five cards in his left hand and draws a sixth card from his deck. He then places the sixth card next to the fifth card, and then picks up the fifth card in his hand, but the sixth card remains in the same position, without its position being affected by the fifth card being picked up. (00:12:32)
Revealing mistake: After the Shadow Duelist summons Infernal Queen Archfiend, Jaden says, "An Archfiend monster?" and the shot cuts back to the Shadow Duelist saying with that card on the field, every monster with Archfiend in its name gain 1000 attack points. In this shot, take note of the cards he is holding in his hand. He only appears to be holding onto two of the cards, but every other card in his hand appears to be held perfectly fine despite him not holding onto them. (00:12:41)
Revealing mistake: After the Shadow Duelist has activated the effect of Terrorking Archfiend and the flame has landed on the ball labelled 2, just as he says, "Mirror Gate is shattered", the card shown on his duel disk is misshapen, where two corners of the card are curved, instead of being straight. (00:16:23)
Duel Monsters Spirit Day - S1-E42
Revealing mistake: At the start of the episode, when each of the dorms are shown celebrating at their respective festivals, all the background extras are shown standing completely still, despite the primary characters moving around.
Revealing mistake: When Pierre says "You're only extending your fate, my Cherie, and not even by that long", the shot cuts to Alexis, shown from the side of her face. In the background, Crowler and Sheppard can be seen sitting in the seating area, but their bodies don't appear to be aligned with the seats and are shown passing onto the seat next to them. (00:14:02)
Champion or Chazz-Been? - S2-E2
Revealing mistake: After Bonaparte has introduced Reginald, it cuts to Jaden, Syrus, Alexis and Crowler sitting in the seating area. On the third row are two Slifer Red students. The first is looking at his cards, while the second is looking at the first student's cards as well. Later on, when Reginald has Gilford the Legend attack Chazz, it cuts to Jaden saying "Here we go", and those two students are in the exact same position, looking at the cards. Clearly the same animation was reused on both occasions. (00:03:58 - 00:11:03)
Revealing mistake: While Syrus and Hassleberry are calling for Jaden, there is a shot of a cliffside, that then pans upward to reveal the back side of the Slifer Red dorm. The windows on the left side of the dorm appear to have been drawn wrong, as they are smaller than the windows on the right side, even though they are all supposed to be the same size. (00:00:03)
Don't Fear the Reaper - S2-E39
Revealing mistake: After Jaden summons Dandelion in defence mode, he places a card face down. When he goes to insert the card into the slot on his duel disk, his hand doesn't appear to align with the duel disk. His hand appears to pass over the spherical red light on the duel disk, and not the card slot. (00:13:02)
Revealing mistake: At the start of the duel, in the shot of Alexis saying "If you give me the key now...", the Society of Light dorm members can be seen sitting in the seating area in the background. On the front row, there appears to be two students merged into one seat. (00:11:50)
The Hands of Justice: Part 1 - S2-E50
Revealing mistake: Right before Chancellor Shepherd briefs the students about the tournament, there is a shot of Obelisk Blue and Ra Yellow students around the outside of the building. Later in the episode, after Zane gives his medal to Blair, the scene cuts to outside Duel Academy, and the exact same shot of the Obelisk Blue and Ra Yellow students has been repeated a second time. (00:02:48 - 00:08:45)
Revealing mistake: When the main characters are in the other dimension, they are shown walking on sand quite a lot, but they never make any footprints when walking across it.
Inter-Dimension Detention - S3-E16
Revealing mistake: When Chazz says Jaden can have his bed, a weird animation error occurs regarding the bed. There is a white bedsheet that covers the mattress, and a small shadow can be seen underneath the pillow and duvet. When he starts to get up, the bedsheet momentarily switches to the colour of the shadow midway through the shot. (00:06:10)