Factual error: There indeed was a moment in the game (vs. USSR) where Jim Craig was shaken up, but contrary to what's shown in the movie, the hit did not happen as the Soviets scored a goal. Furthermore, if a goalie is that flagrantly knocked down and out so that a teammate can get a shot off, it should be a two-minute penalty for "goaltender interference" and the goal disallowed.
Factual error: When Coach Herb Brooks is seen walking through the Olympic Village, Italian athletes are seen walking by with their green Olympic team jackets on. It says "Italy" on the backs of their jacket, but countries use their OWN language when putting their names on their jackets. Italy always goes by "Italia" on their uniforms.
Continuity mistake: There is a scene during the training camp in which we see a manager of the team crossing off players names with a blue pen. We can see him crossing the same name off twice in different shots.
Factual error: In the movie, after Mark Johnson scores the last-second goal in the first period against the Soviet Union, the ref indicates that the goal counts and time has expired. Both teams therefore go back to the dressing rooms. In the actual game, the ref ordered the timekeeper to put one second back on the clock, and called the players (most of whom had already gone back to the dressing rooms) back out to the ice for a face-off, to make the end of the period official.
Continuity mistake: During the game against the Soviet Union, the US team ties up the score at 3-3. As Al Michaels comments on the tied score the crowd is panned and the scoreboard reads 4-3, which actually happens a few minutes later in the game. The digits are hard to read, but if you look closely enough, the mistake is detectable.
Factual error: The film was excellent throughout in duplicating the hockey equipment that the players used during the late 1970s and early 1980s - with one notable exception - the players are wearing CCM helmets from the late 1990's instead of the models worn in 1979/80.
Factual error: In several scenes showing Ken Morrow #3, he is shown as being a left handed shooter.He was actually a right handed shooter.
Factual error: After Baker scores the last-minute tying goal against Sweden, we see the opening of one of the ABC television broadcasts of the Olympics as it appeared in 1980. The specific arrangement of the Olympic Fanfare music we hear, however, did not exist until a few years later. It's an arrangement by John Williams that was made for the 1984 Olympics. The crash cymbals and chimes that accompany the opening tympani notes give it away.
Character mistake: While watching a documentary about the Soviet team Herb Brooks says that the Soviets had had 42 games in the last three months with 42 wins. This was supposed to be said in 1979. In the whole of 1979 Team USSR played 24 games only, winning 23 of them and losing Game 1 of the 1979 Challenge Cup, to the NHL All-Star team.
Factual error: Equipment: mostly inaccurate. Locker room scenes show many shoulder pads from late 1980's/early 1990's (floating shoulder caps). Pants are modern, off the shelf CCM's. Goalie chest protectors are from later in the 1980's (at least). They should be the earlier type, such as a Cooper SB 95 and chest protector combination. Pre-Olympic gloves are modern (laughable) shiny vinyl, and the Olympic tournament gloves are simply current CCM pro gloves - right off the shelf, with a re-sewn cuff to make them look older. Also note that the finger wart colors are opposite the 1980 gloves - they should be top white, bottom red. As noted before, the helmets are modern. Opposing team gloves inaccurate/many spray painted early 1990's Cooper solid back roll gloves. In a scene from the Sweden game, there is player with gloves who's cuff-roll says "Koho," but the glove have CCM stripes. And Sweden's 1980 Jofa helmets were royal blue (standard Jofa colors), not navy blue.
Factual error: In the movie, Ken Dryden says something like, "In Madison Square Garden this team played very tentative hockey, very much in awe of the Soviet team. Tonight, they're playing like they're not in awe of anybody." He actually said that during team USA's 7-3 rout of Czechoslovakia.
Other mistake: Just before the second period against the USSR, we see a couple of shots of the benched Soviet starting goaltender Vladislav Tretiak. His hair is dry and combed, and there is no sign of perspiration, despite having just played the whole first period. After the game is over, we see a shot of the Soviet players watching the Americans celebrate. This time Tretiak's hair is wet and his face is sweaty. Shouldn't it be the other way around (i.e., hair is wet after playing one period, then dry after sitting on the bench for two periods)?
Character mistake: While waiting for the plane with Team USA Herb Brooks watches TV news reporting that the NHL All-Star team has been defeated by the Soviets 6-0 in Game 3 of the 1979 Challenge Cup. The 1979 Challenge Cup took place in February, and Herb Brooks became the Team USA Coach only in June.