Continuity mistake: Throughout the various episodes set at the sport facility near Yomiuriland for the final phase of the elementary school tournament, the ferris wheel changes size and number of its carts, and sometimes coloring.
Factual error: Blanket statement for most of the series; 90% of the tackles and blocks shown in the anime would never fly in a real soccer match. Some are particularly outrageous and deserve separate mention, but in general everyone's defense is careless at best, and downright criminal at their worst. Take Kojiro Hyuga's introduction; his 'dribbling' involves shoving the opponent off and the challenges for the ball end up with the opponents bleeding and with torn socks. Any ref would stop this sort of 'play' right away.
Factual error: During the series it's routine for powerful shoots to rip through the net. Needless to say, that can't happen with human strength. In later seasons there are shots that even leave craters in cement walls. Remember, nobody in this series has superpowers. It's supposed to be dramatic and over exaggerated in how the whole pitch feats play out, but those holes in the wall are real.
Character mistake: For being such a football fan, Tsubasa surely keeps poor care of his gear, since he goes everywhere wearing football boots, and the studs are certainly not suited for 24/7 usage on asphalt. Even worse for Genzo, who for no reason walks around the city in his full goalkeeper uniform and boots. He's a professional with a private coach who is very strict. Besides...who would keep goalkeeper gloves off the pitch all the time?
Other mistake: Star keeper Genzo Wakabayashi has a trademark hat with his name and a cool logo. According to his manga character design he was supposed to wear the Adidas logo, but copyright issues arose and the Nankatsu logo is a great substitute visually - sadly it makes no sense, because he is sporting it already at the beginning of the anime and the team with that logo will be properly formed only later in the series.
Continuity mistake: The inside of the truck Tsubasa and his mom ride in has stuff that change color/arrangement between shots. For instance, there's a beige box on top of the yellow and blue trunk next to Natsuko Ozora that is gone randomly in the aerial shots and when Yayoi is chasing them. (00:02:40)
Factual error: Tsubasa is daydreaming over a picture of Italy winning the 1982 World Cup. The uniform in the photo though has trunks and collars of the wrong color, a yellow that has never been part of any of Italy's sets. And even if it's certainly not a photorealistic cartoon, the features/hairstyles of the team depicted have nothing to do with the winning team; the winning team was not composed of gingers with big perms; the majority had black hair of medium to short length. (00:02:45)
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)
Continuity mistake: Tsubasa moves up the ditch with a diagonal strafing. He then answers Sanae's questions but suddenly on that same ditch, by his feet, Roberto Hongo is resting, sleeping. If he were sleeping on the other side of the road (as it seems when he gets up later) then the feet of the characters in that first shot were facing the wrong way. (00:08:50)
Continuity mistake: When Tsubasa is staring at the soccer grounds sign, it is written with a different layout in different shots. (00:10:10)
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)
Audio problem: When the handball team captain is about to throw, the ball bounces making the sound it'd make if he were bouncing it indoors, not on a grass field. (00:13:40)
Plot hole: Once Wakabayashi wins his challenge against the Nankatsu senior students, he instantly is back at his huge mansion to collect Tsubasa's message. Tsubasa was standing just a few meters away watching The Challenge as it happened, and Genzo had no reason to run away (if anything he was supposed to supervise the team during training), nor he's shown doing that. He's just gone, no explanation. (00:15:20)
Continuity mistake: When Genzo kicks the ball towards Tsubasa, the close-up shows the leg of someone wearing just thick white socks, while Genzo is wearing red pants that don't ride up that high. (00:21:40)
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.
Other mistake: Tsubasa is talking to 'his friend' the football as he does keepie-uppies. He is normally animated pretty decently during that activity, except in the shot when he is telling his friend about Genzo's skills; he is keeping his torso completely immobile, moving just his thighs, which is just physically impossible. A few shots later his torso is still again but at least his thighs are not in frame (the ball is though, what could he possibly be using to juggle it up?). (00:06:10)
