Continuity mistake: During the Triangle Jump (a manoeuvre that virtually any referee would sanction as unsportmanship conduct and dangerous play) one of the Tachibanas, wearing number 10, heads the ball for the other Tachibana...who is wearing number 10 too. (00:20:40)
Other mistake: When the Nankatsu player is injured, Genzo reacts to the event watching it happen through the TV - but he shouldn't be there watching the match, he said he was going to train instead. The next episode in fact shows that he missed the goal and therefore the injury. (00:21:40)
Character mistake: The Tachibana twins' play leading to the second goal is called by the commentator as "on the limit of the offside", but that does not make sense; there are a bunch of players in front of them, it does not come close to being offside. (00:06:50)
Continuity mistake: The players are celebrating their victory. Urabe and Ishizaki in the middle are celebrating, but Urabe has Taki's teeth in the first shot, and in the second there are two Misakis and a Teppei Kisugi behind them - he should be in front of them. (00:01:40)
Plot hole: The whole team went into the match, and the tournament, without knowing its rules. They all are totally surprised by the fact that the top 2 teams qualify from each group. Of course, that's quite impossible, especially since there are veterans in the team, Tsubasa is a football fanatic, Misaki is a clever student of the game, and you just don't walk into a tournament you have prepared for and looked forward to for ages without knowing such a basic fact.
Other mistake: Behind Ishizaki on the bench as he incites Tsubasa in the last action of the episode, Manabu's legs and feet do not link correctly (something went wrong in the drawing, he's sockless all of a sudden and the ankles are much wider than the feet). (00:19:25)