During the game against the Blake Bears you see the first 2 goals scored by the ducks, the score board go form 2-0 to 3-0. Then they score a 3rd goal and the score board goes from 3-0 to 4-0, when only a total of 3 goals were scored.
When Charlie is Rollerblading down the street hill towards the bridge, a blue Camaro turns onto the road to go onto the hill. At the bottom of the hill, the same Blue Camaro turns onto the street again to pass by once more.
The school's ice rink has banners hanging from all over the ceiling and an American flag hanging almost flush to the wall. The flag is hanging vertically with the stars in the top right hand corner, when in fact the proper position of the stars, whether a flag hangs vertically or horizontally, is in the top left corner.
When Dean Portman returns, he 'checks' the blond-haired varsity kid over the boards, where he breaks the glass en route to crashing into some fans. In an NHL game, when the glass is broken, they would stop the game to repair it. There is no understood delay in the JV-Varsity showdown after the glass breakage.
After the coach yells at the Ducks for playing the varsity, Charlie and Fulton skate off the ice on the back of Fulton's jersey says "Fulton" when it should be "Reed." (In the first movie, he is listed as Reed, in D2 in Team USA Jerseys he is listed as Reed, however in the USA Ducks jerseys, he is listed as Fulton.)
The goof item below may give away important plot points.
When Gordon and Charlie spend the day together after Hans passes away, they stop to look at an old high school photo of Bombay. The photo places Gordon in high school (probably his senior year) in 1975. Gordon's infamous penalty shot took place in 1973 when he was only 11 or 12 years old.