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.
Continuity mistake: When the coach of the new Nankatsu team approaches the teacher, she picks the sheet with the players list and her left arm is not shown. In the wider angle the arm is right at the bottom of the sheet. (00:05:10)
Continuity mistake: Sanae is crying and wiping her tears when Tsubasa thanks her, she is happy smiling and clinging to the railing in the background when Roberto compliments Tsubasa, and again crying and wiping in the next shot. (00:21:45)
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)
The Football Is My Best Friend - S1-E4
Other mistake: Shuutetsu's sweeper Shingo Takasugi is the victim of an obvious coloring error during his introduction, and as he kicks the ball from the defense he is shown wearing the purple and blue uniform of the goalkeeper instead of the teal and red of the team jersey. Some international dubs even try to cover the mistake making up a line about him being a substitute keeper in absence of Genzo (but his jersey changes intermittently). (00:08:55)
The Football Is My Best Friend - S1-E4
Other mistake: Look at the bleachers when Ryo tells to the team that they need to examine Shuutetsu's playing; there are 11 players wearing the jersey, plus Tsubasa who is off to watch it running by the railing. Too many for the size of their team. (00:07:25)
Other mistake: The animation of the team laughing at Ryo's joke about scoring 10 goals is botched to the point of the players basically convulsing. (00:12:55)
Audio problem: The Shimada team let out a loud cheer, but the movement happens a good second later only, in the background. (00:05:55)
No Easy Way - S1-E12
Continuity mistake: The finalists are announced; look at the Shimada club. Besides the bad design of their shirts with the name handwritten in western characters that clashes with the anatomy, they are in different poses at the cut. (00:13:25)
No Easy Way - S1-E12
Continuity mistake: Wakabayashi lands on the right ankle, which is not the injured one, and still he does suffers the career-threatening relapse. (00:12:50)
No Easy Way - S1-E12
Other mistake: Izawa's ball for Tsubasa has an impossible trajectory, coming down diagonally to the left after ascending diagonally to the right without curving. (00:07:50)
No Easy Way - S1-E12
Continuity mistake: Urabe tackles the opponent from the side, but in the next shot he's belly down turned 180° compared to the tackle. (or the ball changed direction in a similar fashion). (00:07:30)
Other mistake: Nankatsu doesn't get a corner kick after the keeper fumbled the ball and a midfielder headed it past the line.
Kick-Off for the Future - S1-E3
Other mistake: Spurred by his new deskmate, Tsubasa juggles the ball and sends it with a header right onto the empty seat. Pretty sure it's forbidden in any school to just come to class with a football, but besides that; look at how the football is in view. How tall would the chair have to be for that to happen? Whoever sits on it has no room to put their legs under the desk for sure. (00:10:35)
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.
Continuity mistake: Once Genzo is beaten, the ball is inside the goal towards the right. He walks away, nobody having touched anything, and the ball is towards the left. (00:11:00)
Continuity mistake: An indignant Genzo pushes Tsubasa away from him as he tries to aid him. Tsubasa lands with his back into the goal net, but Genzo pushed him away from the goal. (00:09:30)
Continuity mistake: When Tsubasa hits his header, he is far from the box; Genzo punches away with 4 of his teammates in front of him, but then in the aerial shot there are 13 (!) teammates on the field, about 6 close by, plus... Tsubasa himself. (00:07:55)
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.
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)
