Shortly after the U.S.A. scores its third goal in the match vs. the U.S.S.R., the scoreboard over the center of the rink shows a score of U.S.A. 4 - U.S.S.R. 3.
In the bar, O.C. fills his cup with beer and puts down the empty pitcher and in the next shot he is seen picking it up again and filling his beer.
After the U.S. scores its fourth goal over the Soviets, the long shot of the scoreboard shows the score still at 3-3.
At the end of the 2nd period, the score is 3-2, yet at the start of the 3rd period, the scoreboard reads 2-1.
The net design is not consistent with actual footage of the game.
The size of the ice during the Soviet/USA game at the end of the movie is normal size ice. The actual game took place on Olympic sized ice.
In the game against Sweden when goalie Jim Craig is pulled for the sixth attacker, Mark Johnson is shown being sent in as the extra attacker. In the actual game, Dave Silk was the extra attacker sent in.
Although U of Minnesota did beat Boston U in the 1976 NCAA playoffs, Rob McClanahan was still in high school that year. He played for The U and Coach
Herb Brooks 1977-79. In the movie, O'Callahan tells story that he had been "cheap-shotted" by Mac in '76. Couldn't have happened.
Before the Christmas scene we see a headline from a newspaper that reads: "Soviets Invade Afghanistan". In the next scene it's Christmas. The Russian invasion took place on 29 December 1979.
In the 2nd period on the third Soviet goal by Maltsev, the player is scene crashing into Jim Craig. There was no collision on the play, only a clean goal on a break away. There was a collision on an unrelated play during the 2nd period.
During the match against West Germany, the scoreboard shows that the U.S. is playing the GDR, the English abbreviation for East Germany. The score board in the original game was incorrect - the scoreboard coordinator in the original game made the mistake, not the filmmakers.
The audio of President Jimmy Carter's (presumably) live address is heard during the Christmas scenes of the movie. This famous "crisis of confidence" speech was actually given on 15 July 1979, nowhere near the Christmas season. However, if you listen to the entire radio commentary, it is a "Year in Review" radio program, which would make the playing at Christmas-time accurate.
The hockey competition was NOT a single elimination (knockout) tournament. In the first round, twelve teams were divided into two groups. The top two teams from each group advanced to the medal round and were awarded points based on their result against the other medal round-qualifiers from their group. USSR were seeded first with two points, by virtue of their preliminary round victory over Finland. USA and Sweden tied at the beginning of the competition and had one point each in the initial medal round standings. USA beat USSR and Finland to finish first with a total of five points, USSR beat Sweden in the final game of the competition to finish with four points, Sweden finished third by way of their tie against Finland, which finished fourth with one point.
In the very beginning of the movie, the voice-over newscast is talking about the 26th Amendment to the Constitution, which lowered the voting age to 18. The commentator remarks that the president indicated that he would sign the amendment into law. While constitutional amendments do not require the president's signature to become law (simply a vote of Congress and ratification by three-fourths of the states), presidents can sign amendments after passage by Congress--and Richard Nixon did so for the 26th Amendment, at a ceremony in the East Room of the White House on July 5, 1971.
At the end of the second period when Johnson scores the goal it doesn't actually go in the net. It visibly passed behind the net from the left side and the puck can clearly be heard hitting the boards.
Before Mike Eruzione comes in against the Soviets, John Harrington checks a Russian into the boards. After Eruzione enters, Harrington checks the same guy into the boards in the same spot.
In the end, after they have beaten Finland, at the award ceremony, the other 2 countries receiving medals are Soviet Union and Sweden.
Water bottles were not kept on the nets for the goalies until the late-1980s or early-1990s.
In the final game, someone in the background behind Coach Brooks has an "Under Armour" performance gear hat from the late 1990s.
Throughout the movie, various goaltenders - especially Craig and Tretiak - are shown wearing Tuuk-style blades on their skates. Tuuks for goalie skates were not developed until the mid- to late-80s. In the era of kick saves, plastic blade holders were thought to be too risky for goalie skates.
Jack O'Callahan wears a t-shirt of Harpoon Brewery founded in 1986.
In the shot of the World Trade Center shown before the USA/USSR game at Madison Square Garden, the World Financial Center buildings are surrounding it. These were not built until the mid '80s.
Casey Burnette, the actor playing defenseman Ken Morrow, is clean shaven throughout the entire film. In fact, Morrow reported to camp with a beard and Herb Brooks allowed him to keep it.
Valeri Kharlamov, one of the best Soviet players, ever, is depicted as being a right-handed shot in the movie. He was a left-handed shot in real life.
On the back of his shirt, the player typically called "Kharlamov" in the west, has his name spelled as "Charlamov", which is correct. Sometimes the announcers would pronounce his name "Harlamov". In Russian, when a kh comes at the beginning of a word, it is pronounced like an h. If spelled with "ch" it would be pronounced as "Sharlamov", which almost no one (in the movie or real life) got correct. The "C" in the Russian alphabet is analogous to "S" in the Roman alphabet.
On a power play against the USSR, coach Herb Brooks tells the Smurf Line to get on the ice. The Smurf Line was actually the "Coneheads" Line (Mark Pavelich, John Harrington and Buzz Schneider).