Fighting for a Friend: Part 4 - S4-E28
Continuity mistake: Joey uses his Cyber-Tech Alligator to destroy one of Mai's Cyber Harpie monsters, meaning there were two Cyber Harpies on the field before the attack, but only one after the attack. Only one Cyber Harpie card can be seen on Mai's duel disk after the attack. When Mai says, "You're pretty confident for someone who's about to lose," there are two Cyber Harpie cards on her duel disk, even though there should be one. (00:16:50 - 00:17:20)