At the end of the movie, when Charlie takes the penalty shot, he has no helmet on. No youth hockey league in American would allow a player on the ice without a helmet. Also all leagues forbid half-helmet shields and require cage masks.
Throughout the film, various hockey players are shown on the ice as being both lefty and righty shots. No player is that ambidextrous, nor would they have time to switch sticks randomly while on a shift.
when Gordon is talking to Hans right after the panthers announce they will forfeit the season, the back round it says the cardinals has a record of 8-4-0 and the flames 8-3-1 in the next shot a few seconds later they both have 8-3-1.(about 55 minutes into the movie)
Where the team first get their duck jerseys, Bombay says, "Now we're the ducks," and Goldberg cheerfully throws his arm in the air with his jersey in hand. In the next shot where Bombday says, "the mighty ducks," Goldberg is reaching for his jersey in the box.
When the Ducks are getting fired up before a game, they start chanting 'quack, quack...'. At the beginning of this, Banks is not wearing a glove, but two seconds later, when he jumps on to the ice, he suddenly has gloves on.
In the opening scene, Coach Rielly says to Gordon "Alright Gordon, it's up to you. I don't wanna see any goats around here after the game, you got it? Now you miss this shot, you're not just letting me down you're letting your whole team down too." But then later when we see Gordon skating and thinking about this event Coach Reilly says to him "Alright it's up to you Gordon. Now you miss this shot, you're not just letting your team down, you're letting me down too."
During the championship game, when Coach Bombay is talking about the Flying "V" to Guy, Terry, and Jesse, Jesse's gloves are off. Then Bombay yells for a line change, with Jesse's gloves still off, but only a second later, Jesse jumps over the boards with both gloves on.
When Gordon Bombay is arrested for DWI in Minneapolis, Minnesota, the police officer states that he will be giving him the choice between "breath, blood or urine". While that is the law and practice in the City of Hollywood and the rest of California, it is not the law in Minnesota, where police offer only breath or a choice of "blood or urine". Despite a law to the contrary, many police in Minnesota offer only blood or only urine and the courts have not disapproved.
In the beginning of the movie when Gordon Bombay is coaching D-5, there would be no way this team would be permitted to play with the lack of and/or outdated hockey equipment. Goldberg has no goalie pads, most of his skaters have no full facial protection, no shin pads and the use of bike and football helmets. From at least 1980 all minor hockey programs required kids to wear full face protection.
At the end when one of the Hawks cross-checks Adam Banks from behind. He only receives a two minute penalty. The player should have received a five-minute major and game misconduct, or a match, because an injury resulted from the play.
When Bombay pulls up and sees Fulton practicing his shot in the alley and the puck hits the van window it shatters but does not break apart. This is consistent with safety glass (a piece of glass between two pieces of plastic) that only the windshield is made out of. If a puck actually hit the side window it would have shattered and broken out.
In the opening face-off of the final championship game, the referee places the puck on what is obviously a piece of highly reflective polished silver stainless steel, not white ice, that is painted to look like the markings on a hockey rink. You can tell the difference when the camera quickly switches to an overhead view of the players trying to swipe the puck, the surface is now white with no reflections and the markings are all scraped up from use and are dull in color.
The goof item below may give away important plot points.
When Charlie scores the goal during the penalty shot, his shot is on the ice. When the camera cuts to show the puck going in, it banks high off the post to make it look more like Gordon's original missed shot.