Deliberate mistake: There is a shot of Alexis getting blasted with electricity when Etoile Cyber is attacked by Sparkman. This same shot is reused later in the episode when she attacked directly by Elemental Hero Thunder Giant, as the electricity and Alexis' position in the shot is the same. (00:12:20 - 00:18:36)
Yu-Gi-Oh! GX (2004)
1 deliberate mistake in season 1
Starring: Vinnie Penna, Jesse Hooker, Kanako Irie, Tony Salerno
Graduation Match: Part 1 - S1-E51
Audio problem: After Jaden and Zane shake hands and the duel starts, there is a wide shot of the arena where the students are heard cheering for them. But the students all appear to be sitting completely still and motionless, and their mouths don't move in any way. (00:06:35)
Tag Team Trial: Part 1 - S1-E10
Chancellor Shepherd: Jaden, I'll leave it up to you, son.
Jaden Yuki: Ah, these guys couldn't even beat male pattern baldness so there's no way they're going to be able to beat us.