Revealing mistake: After Steelleg's and Iron Head's song, Steelleg is taken outside for a fight with some thugs. He kicks a ball into the stomach of a guy, making him fly backwards and roll over several times before he slides away on the ground. Look at his neck in the shot from behind - you can see the construction he was dragged by under the shirt.
Continuity mistake: When the Shaolin Team is playing their training match, the rival team chooses to do their "final attack" to the goalkeeper, throwing one of their shoes to him, but he manages to put all of the shoes together making a rapid movement. If you look closely while he's making this movement, you'll see that he catches more than a dozen shoes, and there are even more shoes on the ground, although the rival team has only seven players and each player throws just one shoe.
Revealing mistake: When the Kung Fu team is playing against a football team (before the team that has two women), one of their players is running with the ball stuck to his stomach. He knocks two players down by running into them, and the goalkeeper jumps on him, holding him by his clothes, but he is dragged after the player. You can see him float above the ground for a moment (while holding the player's clothes), just before the goal is made.
Continuity mistake: When the Kung Fu team is playing their first match (the team that beats them up), all the Kung Fu players are getting their powers back. There are clips of each one of them with an explosion behind them. Look at the goalkeeper - in the clip with the explosion, his hair is all messed up, but when he jumps into the goal, his hair is combed.
Continuity mistake: When the brother, who catches the ball with his stomach, has taken over as keeper, you can see him standing with the ball attached to his stomach. The part of his stomach above the ball is covered with clothing. When it cuts you can see his bare stomach where the clothing should be.