Other mistake: Tsubasa's mom calls him because the movers' truck is leaving. He kicks the ball outside the window, and is downstairs to catch it, quite the impossible feat especially when you factor in that he kicked the ball with not much of a vertical trajectory, almost in a straight parabolic pattern out of the window, and meanwhile he also found time to wear and fasten his shoes. And it's not even played up as something strange. (00:03:00)
Other mistake: In the Italian dub, Ryo ("Bruce Harper" as he is known in international versions)'s mom yells at him for running away with the football...but Ryo is not carrying any ball. (00:05:05)
Other mistake: Masaru falls into the river and Tsubasa follows him getting knee-deep and with socks and shoes on, but the moment they step out of the water both are perfectly dry and have no problem or discomfort at all. (00:07:20)
Other mistake: Genzo's challenge invites anyone to score shooting outside the penalty area...but we see that at least the rugby captain is standing inside the box. (00:12:20)
Other mistake: When Tsubasa kicks the soccer ball returning Wakabayashi's shot, the ball goes under the lorry and flies past several drive shafts. (00:21:50)
Other mistake: Tsubasa 'powers' in this episode get nerfed in the rest of the series; he is in elementary school and yet his shot flies literally miles off to land with precision in the arms of Wakabayashi. If he had this power and precision during a match, he'd be superhuman.
Other mistake: The international dubs (Spanish, Italian, from what I understand even Arabian) have the narrator say that Fujisawa (which is where the international dubs set the story instead of the fictional town of Nankatsu) is renowned for its football teams, plural. That's not true, since the only strong team is Genzo's Shutetsu, and the competing team in the local derby loses 10-0 to them, and the prestige the city has comes from their victory in the previous championship tournament.