Factual error: The goal kick after 0-2 in the Nankatsu-Shimada game is illegal, with a (nondescript) player shown kicking the ball forward to himself rather than passing. (00:16:20)
No Easy Way - S1-E12
Factual error: Teppei Kisugi kicks the ball off advancing with the ball without passing to a teammate first. (00:19:45)
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)
The Verification Test - S1-E16
Factual error: Judging by the x-ray of the leg, Genzo wouldn't even be walking without a cane, let alone play. His tibia is shattered. (00:07:20)
Factual error: The world record for high jump from professional adult athletes is barely above 2 meters when we do not consider the Fosbury flop. An 11 years old kid here nonchalantly leaps over the goal net (which is around 2 meters, close to two and half if they use a professional one, slightly less for junior matches), from a big distance and landing on his feet on top of the bar...and it's just an effortless transition before he does the REALLY impressive stuff. These kids are not supposed to be superhuman. (00:14:50)
Blocked Off - S1-E6
Factual error: Genzo concedes a corner. Look when the ball goes out of bounds; the corner flag is misplaced. (00:15:30)
Factual error: In this episode we have a random person showing up and being admitted to the team and playing as substitute on the spot, with nobody protesting. He puts on the (sweat-soaked, presumably!) uniform of another player and just goes ahead without any check from the referee or assistants. Given that the match is between two schools without necessarily having the official football federation involved, it is understandable, but they do not even ask the opposing coach if they are OK with something so obviously outside of any established rule. And they are still playing in a packed stadium, with official referees and even a radio commentator! Only in anime.
Factual error: It's the first leg of a tournament between elementary school players, and people skip work to see it, the city streets are empty because everyone is home watching it (since it is televised, too!)... That just never happens. It is not a world different from our own where everything is based on the sport (like Pokemon).
Factual error: Wakabayashi is seriously injured and everyone is aware of that and acknowledges it, but no substitution is made. That's criminally irresponsible, especially with the team being in the lead. The referee himself couldn't ignore this in a real match, since the player couldn't even perform a goal kick.
Factual error: If we had to go by the pre-kickoff aerial shot, Shuutetsu is playing with a 2-3-5, which is definitely not a normal soccer formation - and we never see during the actual play anything close to the team having 5 forwards. Also, the linesmen are infield instead of behind the sidelines. (00:17:05)
Factual error: Genzo challenges Tsubasa to a rematch, this time in a regular "90 minutes match." They are elementary school students, their matches last only about 40 minutes.