Corrected entry: At the time the film was made, the Celtics team sucked, always finishing low in their division but for movie purposes they are a good team because they made it to the NBA finals. When Mike and Jimmy are talking to Larry Bird they comment on the Celtics real-life situation that they used to be good but are not any more. Then Bird replies saying he hates fans like that who support the team when they are winning and don't support them when they are losing. Obviously forgetting about the movie plot where the Celtics are actually supposed to be a good team that wins most of their matches, get to the NBA Finals and only losing in 7 games to the team with the best player in the league.
Correction: Mike remarks that he and Jimmy stopped liking the Celtics after Larry Bird retired, indicating the Celtics immediately became a bad team (Bird retired in 1992 and the film presumably takes place in 1996). Although the Celtics portrayed in the movie have eventually become a good team, Mike has to keep his bluff going in order to win Lewis Scott over and unfortunately isn't quick enough on his feet to come up with a better lie.
Corrected entry: After running into their friend in the stadium (known as bad luck guy) the Celtics lose a big half-time lead. Daniel Stern said the Celtics were up by 18 points at the hald when he showed up. But the score board showed the Celtics up by 15 points at the half! 54-39.
Correction: This is a character mistake, not a movie mistake. He is mad and venting his frustrations, so it is understandable that he got the score wrong.
Corrected entry: In an NBA finals series, the higher ranked team has home court advantage. The first 2 games are played at one arena, then the next 2 are played at the other team's arena. Game 6 was played in Boston meaning they were the lower ranked team. Yet the dramatic game 7 was also played in Boston. This is impossible because at least one of the final 2 games would have to be played in Utah, regardless of who was ranked higher.
Correction: That used to be the NBA Finals format until 1985. Now the first two games are played at the higher ranked team's arena, the next three games are played at the lower ranked team's arena, and the final two games are played at the higher ranked team's arena. This format is only used in the finals because of the longer travel from the east to west coast.